[TD-1313]<hotfix>: implement getColumns method in the TSDBDatabaseMetadata and...

[TD-1313]<hotfix>: implement getColumns method in the TSDBDatabaseMetadata and update the next method in DatabaseMetaDataResultSet

src/connector/jdbc/pom.xml

@@ -55,6 +55,7 @@
             <version>4.13</version>
             <scope>test</scope>
         </dependency>
+
     </dependencies>
     <build>
         <plugins>

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

src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBDatabaseMetaData.java

@@ -586,7 +586,171 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
 
     public ResultSet getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern)
             throws SQLException {
-		return getEmptyResultSet();
+
+
+        /** 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)