diff --git a/src/connector/jdbc/pom.xml b/src/connector/jdbc/pom.xml
index 36e2fa426b7647b4b2a3543ffa8470c310dc82b2..99409fe27722fb43f9d9fa50a0c0f17b5c1f76be 100755
--- a/src/connector/jdbc/pom.xml
+++ b/src/connector/jdbc/pom.xml
@@ -55,6 +55,7 @@
             <version>4.13</version>
             <scope>test</scope>
         </dependency>
+
     </dependencies>
     <build>
         <plugins>
diff --git a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/DatabaseMetaDataResultSet.java b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/DatabaseMetaDataResultSet.java
index 86938031f6e4a6001bca2c8f2911e6a8f0284cc4..f82c064e751c195eb6327580c285a815346c917b 100644
--- a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/DatabaseMetaDataResultSet.java
+++ b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/DatabaseMetaDataResultSet.java
@@ -67,14 +67,23 @@ public class DatabaseMetaDataResultSet implements ResultSet {
 
     @Override
     public boolean next() throws SQLException {
+//        boolean ret = false;
+//        if (rowDataList.size() > 0) {
+//            ret = rowDataList.iterator().hasNext();
+//            if (ret) {
+//                rowCursor = rowDataList.iterator().next();
+//                cursorRowNumber++;
+//            }
+//        }
+//        return ret;
+
+        /**** add by zyyang 2020-09-29 ****************/
         boolean ret = false;
-        if (rowDataList.size() > 0) {
-            ret = rowDataList.iterator().hasNext();
-            if (ret) {
-                rowCursor = rowDataList.iterator().next();
-                cursorRowNumber++;
-            }
+        if (!rowDataList.isEmpty() && cursorRowNumber < rowDataList.size()) {
+            rowCursor = rowDataList.get(cursorRowNumber++);
+            ret = true;
         }
+
         return ret;
     }
 
@@ -91,7 +100,8 @@ public class DatabaseMetaDataResultSet implements ResultSet {
     @Override
     public String getString(int columnIndex) throws SQLException {
         columnIndex--;
-        return rowCursor.getString(columnIndex, columnMetaDataList.get(columnIndex).getColType());
+        int colType = columnMetaDataList.get(columnIndex).getColType();
+        return rowCursor.getString(columnIndex, colType);
     }
 
     @Override
diff --git a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBDatabaseMetaData.java b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBDatabaseMetaData.java
index 15f66fa2029e7c1bf8a3ecf8ec68b53a8455c648..e5515c24b7a298f0d82f5ad5f880fc1a166f9a3f 100644
--- a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBDatabaseMetaData.java
+++ b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBDatabaseMetaData.java
@@ -20,519 +20,519 @@ import java.util.List;
 
 public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
 
-	private String dbProductName = null;
-	private String url = null;
-	private String userName = null;
-	private Connection conn = null;
-
-	public TSDBDatabaseMetaData(String dbProductName, String url, String userName) {
-		this.dbProductName = dbProductName;
-		this.url = url;
-		this.userName = userName;
-	}
+    private String dbProductName = null;
+    private String url = null;
+    private String userName = null;
+    private Connection conn = null;
+
+    public TSDBDatabaseMetaData(String dbProductName, String url, String userName) {
+        this.dbProductName = dbProductName;
+        this.url = url;
+        this.userName = userName;
+    }
 
-	public void setConnection(Connection conn) {
-		this.conn = conn;
-	}
+    public void setConnection(Connection conn) {
+        this.conn = conn;
+    }
 
-	public <T> T unwrap(Class<T> iface) throws SQLException {
-		return null;
-	}
+    public <T> T unwrap(Class<T> iface) throws SQLException {
+        return null;
+    }
 
-	public boolean isWrapperFor(Class<?> iface) throws SQLException {
-		return false;
-	}
+    public boolean isWrapperFor(Class<?> iface) throws SQLException {
+        return false;
+    }
 
-	public boolean allProceduresAreCallable() throws SQLException {
-		return false;
-	}
+    public boolean allProceduresAreCallable() throws SQLException {
+        return false;
+    }
 
-	public boolean allTablesAreSelectable() throws SQLException {
-		return false;
-	}
+    public boolean allTablesAreSelectable() throws SQLException {
+        return false;
+    }
 
-	public String getURL() throws SQLException {
-		return this.url;
-	}
+    public String getURL() throws SQLException {
+        return this.url;
+    }
 
-	public String getUserName() throws SQLException {
-		return this.userName;
-	}
+    public String getUserName() throws SQLException {
+        return this.userName;
+    }
 
-	public boolean isReadOnly() throws SQLException {
-		return false;
-	}
+    public boolean isReadOnly() throws SQLException {
+        return false;
+    }
 
-	public boolean nullsAreSortedHigh() throws SQLException {
-		return false;
-	}
+    public boolean nullsAreSortedHigh() throws SQLException {
+        return false;
+    }
 
-	public boolean nullsAreSortedLow() throws SQLException {
-		return !nullsAreSortedHigh();
-	}
+    public boolean nullsAreSortedLow() throws SQLException {
+        return !nullsAreSortedHigh();
+    }
 
-	public boolean nullsAreSortedAtStart() throws SQLException {
-		return true;
-	}
+    public boolean nullsAreSortedAtStart() throws SQLException {
+        return true;
+    }
 
-	public boolean nullsAreSortedAtEnd() throws SQLException {
-		return !nullsAreSortedAtStart();
-	}
+    public boolean nullsAreSortedAtEnd() throws SQLException {
+        return !nullsAreSortedAtStart();
+    }
 
-	public String getDatabaseProductName() throws SQLException {
-		return this.dbProductName;
-	}
+    public String getDatabaseProductName() throws SQLException {
+        return this.dbProductName;
+    }
 
-	public String getDatabaseProductVersion() throws SQLException {
-		return "1.5.1";
-	}
+    public String getDatabaseProductVersion() throws SQLException {
+        return "1.5.1";
+    }
 
-	public String getDriverName() throws SQLException {
-		return TSDBDriver.class.getName();
-	}
+    public String getDriverName() throws SQLException {
+        return TSDBDriver.class.getName();
+    }
 
-	public String getDriverVersion() throws SQLException {
-		return "1.0.0";
-	}
+    public String getDriverVersion() throws SQLException {
+        return "1.0.0";
+    }
 
-	public int getDriverMajorVersion() {
-		return 0;
-	}
+    public int getDriverMajorVersion() {
+        return 0;
+    }
 
-	public int getDriverMinorVersion() {
-		return 0;
-	}
+    public int getDriverMinorVersion() {
+        return 0;
+    }
 
-	public boolean usesLocalFiles() throws SQLException {
-		return false;
-	}
+    public boolean usesLocalFiles() throws SQLException {
+        return false;
+    }
 
-	public boolean usesLocalFilePerTable() throws SQLException {
-		return false;
-	}
+    public boolean usesLocalFilePerTable() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsMixedCaseIdentifiers() throws SQLException {
-		return false;
-	}
+    public boolean supportsMixedCaseIdentifiers() throws SQLException {
+        return false;
+    }
 
-	public boolean storesUpperCaseIdentifiers() throws SQLException {
-		return false;
-	}
+    public boolean storesUpperCaseIdentifiers() throws SQLException {
+        return false;
+    }
 
-	public boolean storesLowerCaseIdentifiers() throws SQLException {
-		return false;
-	}
+    public boolean storesLowerCaseIdentifiers() throws SQLException {
+        return false;
+    }
 
-	public boolean storesMixedCaseIdentifiers() throws SQLException {
-		return false;
-	}
+    public boolean storesMixedCaseIdentifiers() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsMixedCaseQuotedIdentifiers() throws SQLException {
-		return false;
-	}
+    public boolean supportsMixedCaseQuotedIdentifiers() throws SQLException {
+        return false;
+    }
 
-	public boolean storesUpperCaseQuotedIdentifiers() throws SQLException {
-		return false;
-	}
+    public boolean storesUpperCaseQuotedIdentifiers() throws SQLException {
+        return false;
+    }
 
-	public boolean storesLowerCaseQuotedIdentifiers() throws SQLException {
-		return false;
-	}
+    public boolean storesLowerCaseQuotedIdentifiers() throws SQLException {
+        return false;
+    }
 
-	public boolean storesMixedCaseQuotedIdentifiers() throws SQLException {
-		return false;
-	}
+    public boolean storesMixedCaseQuotedIdentifiers() throws SQLException {
+        return false;
+    }
 
-	public String getIdentifierQuoteString() throws SQLException {
-		return " ";
-	}
+    public String getIdentifierQuoteString() throws SQLException {
+        return " ";
+    }
 
-	public String getSQLKeywords() throws SQLException {
-		return null;
-	}
+    public String getSQLKeywords() throws SQLException {
+        return null;
+    }
 
-	public String getNumericFunctions() throws SQLException {
-		return null;
-	}
+    public String getNumericFunctions() throws SQLException {
+        return null;
+    }
 
-	public String getStringFunctions() throws SQLException {
-		return null;
-	}
+    public String getStringFunctions() throws SQLException {
+        return null;
+    }
 
-	public String getSystemFunctions() throws SQLException {
-		return null;
-	}
+    public String getSystemFunctions() throws SQLException {
+        return null;
+    }
 
-	public String getTimeDateFunctions() throws SQLException {
-		return null;
-	}
+    public String getTimeDateFunctions() throws SQLException {
+        return null;
+    }
 
-	public String getSearchStringEscape() throws SQLException {
-		return null;
-	}
+    public String getSearchStringEscape() throws SQLException {
+        return null;
+    }
 
-	public String getExtraNameCharacters() throws SQLException {
-		return null;
-	}
+    public String getExtraNameCharacters() throws SQLException {
+        return null;
+    }
 
-	public boolean supportsAlterTableWithAddColumn() throws SQLException {
-		return true;
-	}
+    public boolean supportsAlterTableWithAddColumn() throws SQLException {
+        return true;
+    }
 
-	public boolean supportsAlterTableWithDropColumn() throws SQLException {
-		return true;
-	}
+    public boolean supportsAlterTableWithDropColumn() throws SQLException {
+        return true;
+    }
 
-	public boolean supportsColumnAliasing() throws SQLException {
-		return true;
-	}
+    public boolean supportsColumnAliasing() throws SQLException {
+        return true;
+    }
 
-	public boolean nullPlusNonNullIsNull() throws SQLException {
-		return false;
-	}
+    public boolean nullPlusNonNullIsNull() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsConvert() throws SQLException {
-		return false;
-	}
+    public boolean supportsConvert() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsConvert(int fromType, int toType) throws SQLException {
-		return false;
-	}
+    public boolean supportsConvert(int fromType, int toType) throws SQLException {
+        return false;
+    }
 
-	public boolean supportsTableCorrelationNames() throws SQLException {
-		return false;
-	}
+    public boolean supportsTableCorrelationNames() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsDifferentTableCorrelationNames() throws SQLException {
-		return false;
-	}
+    public boolean supportsDifferentTableCorrelationNames() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsExpressionsInOrderBy() throws SQLException {
-		return false;
-	}
+    public boolean supportsExpressionsInOrderBy() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsOrderByUnrelated() throws SQLException {
-		return false;
-	}
+    public boolean supportsOrderByUnrelated() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsGroupBy() throws SQLException {
-		return false;
-	}
+    public boolean supportsGroupBy() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsGroupByUnrelated() throws SQLException {
-		return false;
-	}
+    public boolean supportsGroupByUnrelated() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsGroupByBeyondSelect() throws SQLException {
-		return false;
-	}
+    public boolean supportsGroupByBeyondSelect() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsLikeEscapeClause() throws SQLException {
-		return false;
-	}
+    public boolean supportsLikeEscapeClause() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsMultipleResultSets() throws SQLException {
-		return false;
-	}
+    public boolean supportsMultipleResultSets() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsMultipleTransactions() throws SQLException {
-		return false;
-	}
+    public boolean supportsMultipleTransactions() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsNonNullableColumns() throws SQLException {
-		return false;
-	}
+    public boolean supportsNonNullableColumns() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsMinimumSQLGrammar() throws SQLException {
-		return false;
-	}
+    public boolean supportsMinimumSQLGrammar() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsCoreSQLGrammar() throws SQLException {
-		return false;
-	}
+    public boolean supportsCoreSQLGrammar() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsExtendedSQLGrammar() throws SQLException {
-		return false;
-	}
+    public boolean supportsExtendedSQLGrammar() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsANSI92EntryLevelSQL() throws SQLException {
-		return false;
-	}
+    public boolean supportsANSI92EntryLevelSQL() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsANSI92IntermediateSQL() throws SQLException {
-		return false;
-	}
+    public boolean supportsANSI92IntermediateSQL() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsANSI92FullSQL() throws SQLException {
-		return false;
-	}
+    public boolean supportsANSI92FullSQL() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsIntegrityEnhancementFacility() throws SQLException {
-		return false;
-	}
+    public boolean supportsIntegrityEnhancementFacility() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsOuterJoins() throws SQLException {
-		return false;
-	}
+    public boolean supportsOuterJoins() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsFullOuterJoins() throws SQLException {
-		return false;
-	}
+    public boolean supportsFullOuterJoins() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsLimitedOuterJoins() throws SQLException {
-		return false;
-	}
+    public boolean supportsLimitedOuterJoins() throws SQLException {
+        return false;
+    }
 
-	public String getSchemaTerm() throws SQLException {
-		return null;
-	}
+    public String getSchemaTerm() throws SQLException {
+        return null;
+    }
 
-	public String getProcedureTerm() throws SQLException {
-		return null;
-	}
+    public String getProcedureTerm() throws SQLException {
+        return null;
+    }
 
-	public String getCatalogTerm() throws SQLException {
-		return "database";
-	}
+    public String getCatalogTerm() throws SQLException {
+        return "database";
+    }
 
-	public boolean isCatalogAtStart() throws SQLException {
-		return true;
-	}
+    public boolean isCatalogAtStart() throws SQLException {
+        return true;
+    }
 
-	public String getCatalogSeparator() throws SQLException {
-		return ".";
-	}
+    public String getCatalogSeparator() throws SQLException {
+        return ".";
+    }
 
-	public boolean supportsSchemasInDataManipulation() throws SQLException {
-		return false;
-	}
+    public boolean supportsSchemasInDataManipulation() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsSchemasInProcedureCalls() throws SQLException {
-		return false;
-	}
+    public boolean supportsSchemasInProcedureCalls() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsSchemasInTableDefinitions() throws SQLException {
-		return false;
-	}
+    public boolean supportsSchemasInTableDefinitions() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsSchemasInIndexDefinitions() throws SQLException {
-		return false;
-	}
+    public boolean supportsSchemasInIndexDefinitions() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsSchemasInPrivilegeDefinitions() throws SQLException {
-		return false;
-	}
+    public boolean supportsSchemasInPrivilegeDefinitions() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsCatalogsInDataManipulation() throws SQLException {
-		return true;
-	}
+    public boolean supportsCatalogsInDataManipulation() throws SQLException {
+        return true;
+    }
 
-	public boolean supportsCatalogsInProcedureCalls() throws SQLException {
-		return false;
-	}
+    public boolean supportsCatalogsInProcedureCalls() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsCatalogsInTableDefinitions() throws SQLException {
-		return false;
-	}
+    public boolean supportsCatalogsInTableDefinitions() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsCatalogsInIndexDefinitions() throws SQLException {
-		return false;
-	}
+    public boolean supportsCatalogsInIndexDefinitions() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsCatalogsInPrivilegeDefinitions() throws SQLException {
-		return false;
-	}
+    public boolean supportsCatalogsInPrivilegeDefinitions() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsPositionedDelete() throws SQLException {
-		return false;
-	}
+    public boolean supportsPositionedDelete() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsPositionedUpdate() throws SQLException {
-		return false;
-	}
+    public boolean supportsPositionedUpdate() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsSelectForUpdate() throws SQLException {
-		return false;
-	}
+    public boolean supportsSelectForUpdate() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsStoredProcedures() throws SQLException {
-		return false;
-	}
+    public boolean supportsStoredProcedures() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsSubqueriesInComparisons() throws SQLException {
-		return false;
-	}
+    public boolean supportsSubqueriesInComparisons() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsSubqueriesInExists() throws SQLException {
-		return false;
-	}
+    public boolean supportsSubqueriesInExists() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsSubqueriesInIns() throws SQLException {
-		return false;
-	}
+    public boolean supportsSubqueriesInIns() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsSubqueriesInQuantifieds() throws SQLException {
-		return false;
-	}
+    public boolean supportsSubqueriesInQuantifieds() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsCorrelatedSubqueries() throws SQLException {
-		return false;
-	}
+    public boolean supportsCorrelatedSubqueries() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsUnion() throws SQLException {
-		return false;
-	}
+    public boolean supportsUnion() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsUnionAll() throws SQLException {
-		return false;
-	}
+    public boolean supportsUnionAll() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsOpenCursorsAcrossCommit() throws SQLException {
-		return false;
-	}
+    public boolean supportsOpenCursorsAcrossCommit() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsOpenCursorsAcrossRollback() throws SQLException {
-		return false;
-	}
+    public boolean supportsOpenCursorsAcrossRollback() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsOpenStatementsAcrossCommit() throws SQLException {
-		return false;
-	}
+    public boolean supportsOpenStatementsAcrossCommit() throws SQLException {
+        return false;
+    }
 
-	public boolean supportsOpenStatementsAcrossRollback() throws SQLException {
-		return false;
-	}
+    public boolean supportsOpenStatementsAcrossRollback() throws SQLException {
+        return false;
+    }
 
-	public int getMaxBinaryLiteralLength() throws SQLException {
-		return 0;
-	}
+    public int getMaxBinaryLiteralLength() throws SQLException {
+        return 0;
+    }
 
-	public int getMaxCharLiteralLength() throws SQLException {
-		return 0;
-	}
+    public int getMaxCharLiteralLength() throws SQLException {
+        return 0;
+    }
 
-	public int getMaxColumnNameLength() throws SQLException {
-		return 0;
-	}
+    public int getMaxColumnNameLength() throws SQLException {
+        return 0;
+    }
 
-	public int getMaxColumnsInGroupBy() throws SQLException {
-		return 0;
-	}
+    public int getMaxColumnsInGroupBy() throws SQLException {
+        return 0;
+    }
 
-	public int getMaxColumnsInIndex() throws SQLException {
-		return 0;
-	}
+    public int getMaxColumnsInIndex() throws SQLException {
+        return 0;
+    }
 
-	public int getMaxColumnsInOrderBy() throws SQLException {
-		return 0;
-	}
+    public int getMaxColumnsInOrderBy() throws SQLException {
+        return 0;
+    }
 
-	public int getMaxColumnsInSelect() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxColumnsInTable() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxConnections() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxCursorNameLength() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxIndexLength() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxSchemaNameLength() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxProcedureNameLength() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxCatalogNameLength() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxRowSize() throws SQLException {
-		return 0;
-	}
-
-	public boolean doesMaxRowSizeIncludeBlobs() throws SQLException {
-		return false;
-	}
-
-	public int getMaxStatementLength() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxStatements() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxTableNameLength() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxTablesInSelect() throws SQLException {
-		return 0;
-	}
-
-	public int getMaxUserNameLength() throws SQLException {
-		return 0;
-	}
-
-	public int getDefaultTransactionIsolation() throws SQLException {
-		return 0;
-	}
-
-	public boolean supportsTransactions() throws SQLException {
-		return false;
-	}
-
-	public boolean supportsTransactionIsolationLevel(int level) throws SQLException {
-		return false;
-	}
-
-	public boolean supportsDataDefinitionAndDataManipulationTransactions() throws SQLException {
-		return false;
-	}
-
-	public boolean supportsDataManipulationTransactionsOnly() throws SQLException {
-		return false;
-	}
-
-	public boolean dataDefinitionCausesTransactionCommit() throws SQLException {
-		return false;
-	}
-
-	public boolean dataDefinitionIgnoredInTransactions() throws SQLException {
-		return false;
-	}
-
-	public ResultSet getProcedures(String catalog, String schemaPattern, String procedureNamePattern)
-			throws SQLException {
-		throw new SQLException(TSDBConstants.UNSUPPORT_METHOD_EXCEPTIONZ_MSG);
-	}
-
-	public ResultSet getProcedureColumns(String catalog, String schemaPattern, String procedureNamePattern,
-			String columnNamePattern) throws SQLException {
-		throw new SQLException(TSDBConstants.UNSUPPORT_METHOD_EXCEPTIONZ_MSG);
-	}
-
-	public ResultSet getTables(String catalog, String schemaPattern, String tableNamePattern, String[] types)
-			throws SQLException {
-		Statement stmt = null;
-		if (null != conn && !conn.isClosed()) {
-			stmt = conn.createStatement();
-			if (catalog == null || catalog.length() < 1) {
-				catalog = conn.getCatalog();
-			}
+    public int getMaxColumnsInSelect() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxColumnsInTable() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxConnections() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxCursorNameLength() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxIndexLength() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxSchemaNameLength() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxProcedureNameLength() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxCatalogNameLength() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxRowSize() throws SQLException {
+        return 0;
+    }
+
+    public boolean doesMaxRowSizeIncludeBlobs() throws SQLException {
+        return false;
+    }
+
+    public int getMaxStatementLength() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxStatements() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxTableNameLength() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxTablesInSelect() throws SQLException {
+        return 0;
+    }
+
+    public int getMaxUserNameLength() throws SQLException {
+        return 0;
+    }
+
+    public int getDefaultTransactionIsolation() throws SQLException {
+        return 0;
+    }
+
+    public boolean supportsTransactions() throws SQLException {
+        return false;
+    }
+
+    public boolean supportsTransactionIsolationLevel(int level) throws SQLException {
+        return false;
+    }
+
+    public boolean supportsDataDefinitionAndDataManipulationTransactions() throws SQLException {
+        return false;
+    }
+
+    public boolean supportsDataManipulationTransactionsOnly() throws SQLException {
+        return false;
+    }
+
+    public boolean dataDefinitionCausesTransactionCommit() throws SQLException {
+        return false;
+    }
+
+    public boolean dataDefinitionIgnoredInTransactions() throws SQLException {
+        return false;
+    }
+
+    public ResultSet getProcedures(String catalog, String schemaPattern, String procedureNamePattern)
+            throws SQLException {
+        throw new SQLException(TSDBConstants.UNSUPPORT_METHOD_EXCEPTIONZ_MSG);
+    }
+
+    public ResultSet getProcedureColumns(String catalog, String schemaPattern, String procedureNamePattern,
+                                         String columnNamePattern) throws SQLException {
+        throw new SQLException(TSDBConstants.UNSUPPORT_METHOD_EXCEPTIONZ_MSG);
+    }
+
+    public ResultSet getTables(String catalog, String schemaPattern, String tableNamePattern, String[] types)
+            throws SQLException {
+        Statement stmt = null;
+        if (null != conn && !conn.isClosed()) {
+            stmt = conn.createStatement();
+            if (catalog == null || catalog.length() < 1) {
+                catalog = conn.getCatalog();
+            }
             stmt.executeUpdate("use " + catalog);
             ResultSet resultSet0 = stmt.executeQuery("show tables");
             GetTablesResultSet getTablesResultSet = new GetTablesResultSet(resultSet0, catalog, schemaPattern, tableNamePattern, types);
@@ -540,29 +540,29 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
         } else {
             throw new SQLException(TSDBConstants.FixErrMsg(TSDBConstants.JNI_CONNECTION_NULL));
         }
-	}
+    }
 
-	public ResultSet getSchemas() throws SQLException {
-		return getEmptyResultSet();
-	}
+    public ResultSet getSchemas() throws SQLException {
+        return getEmptyResultSet();
+    }
 
-	public ResultSet getCatalogs() throws SQLException {
+    public ResultSet getCatalogs() throws SQLException {
 
-		if (conn != null && !conn.isClosed()) {
-			Statement stmt = conn.createStatement();
-			ResultSet resultSet0 = stmt.executeQuery("show databases");
-			CatalogResultSet resultSet = new CatalogResultSet(resultSet0);
-			return resultSet;
-		} else {
-		    return getEmptyResultSet();
+        if (conn != null && !conn.isClosed()) {
+            Statement stmt = conn.createStatement();
+            ResultSet resultSet0 = stmt.executeQuery("show databases");
+            CatalogResultSet resultSet = new CatalogResultSet(resultSet0);
+            return resultSet;
+        } else {
+            return getEmptyResultSet();
         }
-	}
+    }
 
-	public ResultSet getTableTypes() throws SQLException {
-	    DatabaseMetaDataResultSet resultSet = new DatabaseMetaDataResultSet();
+    public ResultSet getTableTypes() throws SQLException {
+        DatabaseMetaDataResultSet resultSet = new DatabaseMetaDataResultSet();
 
-	    // set up ColumnMetaDataList
-	    List<ColumnMetaData> columnMetaDataList = new ArrayList<ColumnMetaData>(1);
+        // set up ColumnMetaDataList
+        List<ColumnMetaData> columnMetaDataList = new ArrayList<ColumnMetaData>(1);
         ColumnMetaData colMetaData = new ColumnMetaData();
         colMetaData.setColIndex(0);
         colMetaData.setColName("TABLE_TYPE");
@@ -582,220 +582,384 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
         resultSet.setColumnMetaDataList(columnMetaDataList);
         resultSet.setRowDataList(rowDataList);
         return resultSet;
-	}
-
-	public ResultSet getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern)
-			throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getColumnPrivileges(String catalog, String schema, String table, String columnNamePattern)
-			throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getTablePrivileges(String catalog, String schemaPattern, String tableNamePattern)
-			throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getBestRowIdentifier(String catalog, String schema, String table, int scope, boolean nullable)
-			throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getVersionColumns(String catalog, String schema, String table) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getPrimaryKeys(String catalog, String schema, String table) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getImportedKeys(String catalog, String schema, String table) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getExportedKeys(String catalog, String schema, String table) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getCrossReference(String parentCatalog, String parentSchema, String parentTable,
-			String foreignCatalog, String foreignSchema, String foreignTable) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getTypeInfo() throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getIndexInfo(String catalog, String schema, String table, boolean unique, boolean approximate)
-			throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public boolean supportsResultSetType(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean supportsResultSetConcurrency(int type, int concurrency) throws SQLException {
-		return false;
-	}
-
-	public boolean ownUpdatesAreVisible(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean ownDeletesAreVisible(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean ownInsertsAreVisible(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean othersUpdatesAreVisible(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean othersDeletesAreVisible(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean othersInsertsAreVisible(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean updatesAreDetected(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean deletesAreDetected(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean insertsAreDetected(int type) throws SQLException {
-		return false;
-	}
-
-	public boolean supportsBatchUpdates() throws SQLException {
-		return false;
-	}
-
-	public ResultSet getUDTs(String catalog, String schemaPattern, String typeNamePattern, int[] types)
-			throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public Connection getConnection() throws SQLException {
-		return null;
-	}
-
-	public boolean supportsSavepoints() throws SQLException {
-		return false;
-	}
-
-	public boolean supportsNamedParameters() throws SQLException {
-		return false;
-	}
-
-	public boolean supportsMultipleOpenResults() throws SQLException {
-		return false;
-	}
-
-	public boolean supportsGetGeneratedKeys() throws SQLException {
-		return false;
-	}
-
-	public ResultSet getSuperTypes(String catalog, String schemaPattern, String typeNamePattern) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getSuperTables(String catalog, String schemaPattern, String tableNamePattern) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getAttributes(String catalog, String schemaPattern, String typeNamePattern,
-			String attributeNamePattern) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public boolean supportsResultSetHoldability(int holdability) throws SQLException {
-		return false;
-	}
-
-	public int getResultSetHoldability() throws SQLException {
-		return 0;
-	}
-
-	public int getDatabaseMajorVersion() throws SQLException {
-		return 0;
-	}
-
-	public int getDatabaseMinorVersion() throws SQLException {
-		return 0;
-	}
-
-	public int getJDBCMajorVersion() throws SQLException {
-		return 0;
-	}
-
-	public int getJDBCMinorVersion() throws SQLException {
-		return 0;
-	}
-
-	public int getSQLStateType() throws SQLException {
-		return 0;
-	}
-
-	public boolean locatorsUpdateCopy() throws SQLException {
-		return false;
-	}
-
-	public boolean supportsStatementPooling() throws SQLException {
-		return false;
-	}
-
-	public RowIdLifetime getRowIdLifetime() throws SQLException {
-		return null;
-	}
-
-	public ResultSet getSchemas(String catalog, String schemaPattern) throws SQLException {
-		return null;
-	}
-
-	public boolean supportsStoredFunctionsUsingCallSyntax() throws SQLException {
-		return false;
-	}
-
-	public boolean autoCommitFailureClosesAllResultSets() throws SQLException {
-		return false;
-	}
-
-	public ResultSet getClientInfoProperties() throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getFunctions(String catalog, String schemaPattern, String functionNamePattern)
-			throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getFunctionColumns(String catalog, String schemaPattern, String functionNamePattern,
-			String columnNamePattern) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public ResultSet getPseudoColumns(String catalog, String schemaPattern, String tableNamePattern,
-			String columnNamePattern) throws SQLException {
-		return getEmptyResultSet();
-	}
-
-	public boolean generatedKeyAlwaysReturned() throws SQLException {
-		return false;
-	}
-
-	private ResultSet getEmptyResultSet() {
-		return new EmptyResultSet();
-	}
+    }
+
+    public ResultSet getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern)
+            throws SQLException {
+
+
+        /** add by zyyang **********/
+        Statement stmt = null;
+        if (null != conn && !conn.isClosed()) {
+            stmt = conn.createStatement();
+            if (catalog == null || catalog.length() < 1) {
+                catalog = conn.getCatalog();
+            }
+            stmt.executeUpdate("use " + catalog);
+
+            DatabaseMetaDataResultSet resultSet = new DatabaseMetaDataResultSet();
+            // set up ColumnMetaDataList
+            List<ColumnMetaData> columnMetaDataList = new ArrayList<>(24);
+            columnMetaDataList.add(null);
+            columnMetaDataList.add(null);
+            // add TABLE_NAME
+            ColumnMetaData colMetaData = new ColumnMetaData();
+            colMetaData.setColIndex(3);
+            colMetaData.setColName("TABLE_NAME");
+            colMetaData.setColSize(193);
+            colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_BINARY);
+            columnMetaDataList.add(colMetaData);
+            // add COLUMN_NAME
+            colMetaData = new ColumnMetaData();
+            colMetaData.setColIndex(4);
+            colMetaData.setColName("COLUMN_NAME");
+            colMetaData.setColSize(65);
+            colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_BINARY);
+            columnMetaDataList.add(colMetaData);
+            // add DATA_TYPE
+            colMetaData = new ColumnMetaData();
+            colMetaData.setColIndex(5);
+            colMetaData.setColName("DATA_TYPE");
+            colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
+            columnMetaDataList.add(colMetaData);
+            // add TYPE_NAME
+            colMetaData = new ColumnMetaData();
+            colMetaData.setColIndex(6);
+            colMetaData.setColName("TYPE_NAME");
+            colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_BINARY);
+            columnMetaDataList.add(colMetaData);
+            // add COLUMN_SIZE
+            colMetaData = new ColumnMetaData();
+            colMetaData.setColIndex(7);
+            colMetaData.setColName("COLUMN_SIZE");
+            colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
+            columnMetaDataList.add(colMetaData);
+            // add BUFFER_LENGTH ,not used
+            columnMetaDataList.add(null);
+            // add DECIMAL_DIGITS
+            colMetaData = new ColumnMetaData();
+            colMetaData.setColIndex(9);
+            colMetaData.setColName("DECIMAL_DIGITS");
+            colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
+            columnMetaDataList.add(colMetaData);
+            // add NUM_PREC_RADIX
+            colMetaData = new ColumnMetaData();
+            colMetaData.setColIndex(10);
+            colMetaData.setColName("NUM_PREC_RADIX");
+            colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
+            columnMetaDataList.add(colMetaData);
+            // add NULLABLE
+            colMetaData = new ColumnMetaData();
+            colMetaData.setColIndex(11);
+            colMetaData.setColName("NULLABLE");
+            colMetaData.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
+            columnMetaDataList.add(colMetaData);
+
+            resultSet.setColumnMetaDataList(columnMetaDataList);
+
+            // set up rowDataList
+            ResultSet resultSet0 = stmt.executeQuery("describe " + tableNamePattern);
+            List<TSDBResultSetRowData> rowDataList = new ArrayList<>();
+            int index = 0;
+            while (resultSet0.next()) {
+                TSDBResultSetRowData rowData = new TSDBResultSetRowData(24);
+                // set TABLE_NAME
+                rowData.setString(2, tableNamePattern);
+                // set COLUMN_NAME
+                rowData.setString(3, resultSet0.getString(1));
+                // set DATA_TYPE
+                String typeName = resultSet0.getString(2);
+                rowData.setInt(4, getDataType(typeName));
+                // set TYPE_NAME
+                rowData.setString(5, typeName);
+                // set COLUMN_SIZE
+                int length = resultSet0.getInt(3);
+                rowData.setInt(6, getColumnSize(typeName, length));
+                // set DECIMAL_DIGITS
+                rowData.setInt(8, getDecimalDigits(typeName));
+                // set NUM_PREC_RADIX
+                rowData.setInt(9, 10);
+                // set NULLABLE
+                rowData.setInt(10, getNullable(index, typeName));
+                rowDataList.add(rowData);
+                index++;
+            }
+            resultSet.setRowDataList(rowDataList);
+
+//            GetColumnsResultSet getColumnsResultSet = new GetColumnsResultSet(resultSet0, catalog, schemaPattern, tableNamePattern, columnNamePattern);
+//            return getColumnsResultSet;
+//            DatabaseMetaDataResultSet resultSet = new DatabaseMetaDataResultSet();
+            return resultSet;
+        } else {
+            throw new SQLException(TSDBConstants.FixErrMsg(TSDBConstants.JNI_CONNECTION_NULL));
+        }
+
+        /*************************/
+
+//        return getEmptyResultSet();
+    }
+
+    private int getNullable(int index, String typeName) {
+        if (index == 0 && "TIMESTAMP".equals(typeName))
+            return DatabaseMetaData.columnNoNulls;
+        return DatabaseMetaData.columnNullable;
+    }
+
+    private int getColumnSize(String typeName, int length) {
+        switch (typeName) {
+            case "TIMESTAMP":
+                return 23;
+
+            default:
+                return 0;
+        }
+    }
+
+    private int getDecimalDigits(String typeName) {
+        switch (typeName) {
+            case "FLOAT":
+                return 5;
+            case "DOUBLE":
+                return 9;
+            default:
+                return 0;
+        }
+    }
+
+    private int getDataType(String typeName) {
+        switch (typeName) {
+            case "TIMESTAMP":
+                return Types.TIMESTAMP;
+            case "INT":
+                return Types.INTEGER;
+            case "BIGINT":
+                return Types.BIGINT;
+            case "FLOAT":
+                return Types.FLOAT;
+            case "DOUBLE":
+                return Types.DOUBLE;
+            case "BINARY":
+                return Types.BINARY;
+            case "SMALLINT":
+                return Types.SMALLINT;
+            case "TINYINT":
+                return Types.TINYINT;
+            case "BOOL":
+                return Types.BOOLEAN;
+            case "NCHAR":
+                return Types.NCHAR;
+            default:
+                return Types.NULL;
+        }
+    }
+
+    public ResultSet getColumnPrivileges(String catalog, String schema, String table, String columnNamePattern)
+            throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getTablePrivileges(String catalog, String schemaPattern, String tableNamePattern)
+            throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getBestRowIdentifier(String catalog, String schema, String table, int scope, boolean nullable)
+            throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getVersionColumns(String catalog, String schema, String table) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getPrimaryKeys(String catalog, String schema, String table) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getImportedKeys(String catalog, String schema, String table) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getExportedKeys(String catalog, String schema, String table) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getCrossReference(String parentCatalog, String parentSchema, String parentTable,
+                                       String foreignCatalog, String foreignSchema, String foreignTable) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getTypeInfo() throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getIndexInfo(String catalog, String schema, String table, boolean unique, boolean approximate)
+            throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public boolean supportsResultSetType(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean supportsResultSetConcurrency(int type, int concurrency) throws SQLException {
+        return false;
+    }
+
+    public boolean ownUpdatesAreVisible(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean ownDeletesAreVisible(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean ownInsertsAreVisible(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean othersUpdatesAreVisible(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean othersDeletesAreVisible(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean othersInsertsAreVisible(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean updatesAreDetected(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean deletesAreDetected(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean insertsAreDetected(int type) throws SQLException {
+        return false;
+    }
+
+    public boolean supportsBatchUpdates() throws SQLException {
+        return false;
+    }
+
+    public ResultSet getUDTs(String catalog, String schemaPattern, String typeNamePattern, int[] types)
+            throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public Connection getConnection() throws SQLException {
+        return null;
+    }
+
+    public boolean supportsSavepoints() throws SQLException {
+        return false;
+    }
+
+    public boolean supportsNamedParameters() throws SQLException {
+        return false;
+    }
+
+    public boolean supportsMultipleOpenResults() throws SQLException {
+        return false;
+    }
+
+    public boolean supportsGetGeneratedKeys() throws SQLException {
+        return false;
+    }
+
+    public ResultSet getSuperTypes(String catalog, String schemaPattern, String typeNamePattern) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getSuperTables(String catalog, String schemaPattern, String tableNamePattern) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getAttributes(String catalog, String schemaPattern, String typeNamePattern,
+                                   String attributeNamePattern) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public boolean supportsResultSetHoldability(int holdability) throws SQLException {
+        return false;
+    }
+
+    public int getResultSetHoldability() throws SQLException {
+        return 0;
+    }
+
+    public int getDatabaseMajorVersion() throws SQLException {
+        return 0;
+    }
+
+    public int getDatabaseMinorVersion() throws SQLException {
+        return 0;
+    }
+
+    public int getJDBCMajorVersion() throws SQLException {
+        return 0;
+    }
+
+    public int getJDBCMinorVersion() throws SQLException {
+        return 0;
+    }
+
+    public int getSQLStateType() throws SQLException {
+        return 0;
+    }
+
+    public boolean locatorsUpdateCopy() throws SQLException {
+        return false;
+    }
+
+    public boolean supportsStatementPooling() throws SQLException {
+        return false;
+    }
+
+    public RowIdLifetime getRowIdLifetime() throws SQLException {
+        return null;
+    }
+
+    public ResultSet getSchemas(String catalog, String schemaPattern) throws SQLException {
+        return null;
+    }
+
+    public boolean supportsStoredFunctionsUsingCallSyntax() throws SQLException {
+        return false;
+    }
+
+    public boolean autoCommitFailureClosesAllResultSets() throws SQLException {
+        return false;
+    }
+
+    public ResultSet getClientInfoProperties() throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getFunctions(String catalog, String schemaPattern, String functionNamePattern)
+            throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getFunctionColumns(String catalog, String schemaPattern, String functionNamePattern,
+                                        String columnNamePattern) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public ResultSet getPseudoColumns(String catalog, String schemaPattern, String tableNamePattern,
+                                      String columnNamePattern) throws SQLException {
+        return getEmptyResultSet();
+    }
+
+    public boolean generatedKeyAlwaysReturned() throws SQLException {
+        return false;
+    }
+
+    private ResultSet getEmptyResultSet() {
+        return new EmptyResultSet();
+    }
 }
\ No newline at end of file