diff --git a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/AbstractDatabaseMetaData.java b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/AbstractDatabaseMetaData.java
index 3c9c784f594d6cb022267c2ff1cd848c26f53ac3..7dbb62d8496e9ae9b758c1a6440531e15e352dc9 100644
--- a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/AbstractDatabaseMetaData.java
+++ b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/AbstractDatabaseMetaData.java
@@ -77,8 +77,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
     }
 
     public boolean supportsMixedCaseIdentifiers() throws SQLException {
-        //像database、table这些对象的标识符，在存储时是否采用大小写混合的模式
-        return false;
+        return false;   //像database、table这些对象的标识符，在存储时是否采用大小写混合的模式
     }
 
     public boolean storesUpperCaseIdentifiers() throws SQLException {
@@ -514,7 +513,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col6 = new ColumnMetaData();
         col6.setColIndex(colIndex);
         col6.setColName("TYPE_CAT");
-        col6.setColType(Types.NCHAR);
+        col6.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col6;
     }
 
@@ -522,7 +521,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col7 = new ColumnMetaData();
         col7.setColIndex(colIndex);
         col7.setColName("TYPE_SCHEM");
-        col7.setColType(Types.NCHAR);
+        col7.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col7;
     }
 
@@ -530,7 +529,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col8 = new ColumnMetaData();
         col8.setColIndex(colIndex);
         col8.setColName("TYPE_NAME");
-        col8.setColType(Types.NCHAR);
+        col8.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col8;
     }
 
@@ -538,7 +537,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col9 = new ColumnMetaData();
         col9.setColIndex(colIndex);
         col9.setColName("SELF_REFERENCING_COL_NAME");
-        col9.setColType(Types.NCHAR);
+        col9.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col9;
     }
 
@@ -546,7 +545,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col10 = new ColumnMetaData();
         col10.setColIndex(colIndex);
         col10.setColName("REF_GENERATION");
-        col10.setColType(Types.NCHAR);
+        col10.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col10;
     }
 
@@ -592,7 +591,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col4 = new ColumnMetaData();
         col4.setColIndex(colIndex);
         col4.setColName("TABLE_TYPE");
-        col4.setColType(Types.NCHAR);
+        col4.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col4;
     }
 
@@ -734,7 +733,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col1 = new ColumnMetaData();
         col1.setColIndex(colIndex);
         col1.setColName("TABLE_CAT");
-        col1.setColType(Types.NCHAR);
+        col1.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col1;
     }
 
@@ -742,7 +741,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col2 = new ColumnMetaData();
         col2.setColIndex(colIndex);
         col2.setColName("TABLE_SCHEM");
-        col2.setColType(Types.NCHAR);
+        col2.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col2;
     }
 
@@ -751,7 +750,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         col3.setColIndex(colIndex);
         col3.setColName("TABLE_NAME");
         col3.setColSize(193);
-        col3.setColType(Types.NCHAR);
+        col3.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col3;
     }
 
@@ -760,7 +759,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         col4.setColIndex(colIndex);
         col4.setColName("COLUMN_NAME");
         col4.setColSize(65);
-        col4.setColType(Types.NCHAR);
+        col4.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col4;
     }
 
@@ -768,7 +767,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col5 = new ColumnMetaData();
         col5.setColIndex(colIndex);
         col5.setColName("DATA_TYPE");
-        col5.setColType(Types.INTEGER);
+        col5.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
         return col5;
     }
 
@@ -776,7 +775,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col7 = new ColumnMetaData();
         col7.setColIndex(7);
         col7.setColName("COLUMN_SIZE");
-        col7.setColType(Types.INTEGER);
+        col7.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
         return col7;
     }
 
@@ -791,7 +790,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col9 = new ColumnMetaData();
         col9.setColIndex(9);
         col9.setColName("DECIMAL_DIGITS");
-        col9.setColType(Types.INTEGER);
+        col9.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
         return col9;
     }
 
@@ -799,7 +798,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col10 = new ColumnMetaData();
         col10.setColIndex(10);
         col10.setColName("NUM_PREC_RADIX");
-        col10.setColType(Types.INTEGER);
+        col10.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
         return col10;
     }
 
@@ -807,7 +806,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col11 = new ColumnMetaData();
         col11.setColIndex(11);
         col11.setColName("NULLABLE");
-        col11.setColType(Types.INTEGER);
+        col11.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
         return col11;
     }
 
@@ -815,7 +814,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col12 = new ColumnMetaData();
         col12.setColIndex(colIndex);
         col12.setColName("REMARKS");
-        col12.setColType(Types.NCHAR);
+        col12.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col12;
     }
 
@@ -823,7 +822,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col13 = new ColumnMetaData();
         col13.setColIndex(13);
         col13.setColName("COLUMN_DEF");
-        col13.setColType(Types.NCHAR);
+        col13.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col13;
     }
 
@@ -831,7 +830,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col14 = new ColumnMetaData();
         col14.setColIndex(14);
         col14.setColName("SQL_DATA_TYPE");
-        col14.setColType(Types.INTEGER);
+        col14.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
         return col14;
     }
 
@@ -839,7 +838,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col15 = new ColumnMetaData();
         col15.setColIndex(15);
         col15.setColName("SQL_DATETIME_SUB");
-        col15.setColType(Types.INTEGER);
+        col15.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
         return col15;
     }
 
@@ -847,7 +846,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col16 = new ColumnMetaData();
         col16.setColIndex(16);
         col16.setColName("CHAR_OCTET_LENGTH");
-        col16.setColType(Types.INTEGER);
+        col16.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
         return col16;
     }
 
@@ -855,7 +854,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col17 = new ColumnMetaData();
         col17.setColIndex(17);
         col17.setColName("ORDINAL_POSITION");
-        col17.setColType(Types.INTEGER);
+        col17.setColType(TSDBConstants.TSDB_DATA_TYPE_INT);
         return col17;
     }
 
@@ -863,7 +862,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col18 = new ColumnMetaData();
         col18.setColIndex(18);
         col18.setColName("IS_NULLABLE");
-        col18.setColType(Types.NCHAR);
+        col18.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col18;
     }
 
@@ -871,7 +870,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col19 = new ColumnMetaData();
         col19.setColIndex(19);
         col19.setColName("SCOPE_CATALOG");
-        col19.setColType(Types.NCHAR);
+        col19.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col19;
     }
 
@@ -879,7 +878,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col20 = new ColumnMetaData();
         col20.setColIndex(20);
         col20.setColName("SCOPE_SCHEMA");
-        col20.setColType(Types.NCHAR);
+        col20.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col20;
     }
 
@@ -887,7 +886,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col21 = new ColumnMetaData();
         col21.setColIndex(21);
         col21.setColName("SCOPE_TABLE");
-        col21.setColType(Types.NCHAR);
+        col21.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col21;
     }
 
@@ -903,7 +902,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col23 = new ColumnMetaData();
         col23.setColIndex(23);
         col23.setColName("IS_AUTOINCREMENT");
-        col23.setColType(Types.NCHAR);
+        col23.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col23;
     }
 
@@ -911,7 +910,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col24 = new ColumnMetaData();
         col24.setColIndex(24);
         col24.setColName("IS_GENERATEDCOLUMN");
-        col24.setColType(Types.NCHAR);
+        col24.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col24;
     }
 
@@ -1205,7 +1204,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col5 = new ColumnMetaData();
         col5.setColIndex(colIndex);
         col5.setColName("KEY_SEQ");
-        col5.setColType(Types.SMALLINT);
+        col5.setColType(TSDBConstants.TSDB_DATA_TYPE_SMALLINT);
         return col5;
     }
 
@@ -1213,7 +1212,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col6 = new ColumnMetaData();
         col6.setColIndex(colIndex);
         col6.setColName("PK_NAME");
-        col6.setColType(Types.NCHAR);
+        col6.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col6;
     }
 
@@ -1275,7 +1274,7 @@ public abstract class AbstractDatabaseMetaData extends WrapperImpl implements Da
         ColumnMetaData col4 = new ColumnMetaData();
         col4.setColIndex(colIndex);
         col4.setColName("SUPERTABLE_NAME");
-        col4.setColType(Types.NCHAR);
+        col4.setColType(TSDBConstants.TSDB_DATA_TYPE_NCHAR);
         return col4;
     }
 
diff --git a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/ColumnMetaData.java b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/ColumnMetaData.java
index 14e75f0e09e3403e703658fb503019fefbb6156d..8398c8f84bb8b73b09cd6b7e3e2f27a20f28e8f7 100644
--- a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/ColumnMetaData.java
+++ b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/ColumnMetaData.java
@@ -16,7 +16,7 @@ package com.taosdata.jdbc;
 
 public class ColumnMetaData {
 
-    private int colType = 0;
+    private int colType = 0;         //taosType
     private String colName = null;
     private int colSize = -1;
     private int colIndex = 0;
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 bda3d522123d09ece81384c6eba814c7e548e1ec..db4a5ccaa8fc15aa637363bc3f5e1b34c71dc5be 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
@@ -68,71 +68,61 @@ public class DatabaseMetaDataResultSet extends AbstractResultSet {
     @Override
     public String getString(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return rowCursor.getString(columnIndex, nativeType);
+        return rowCursor.getString(columnIndex, colType);
     }
 
     @Override
     public boolean getBoolean(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return rowCursor.getBoolean(columnIndex, nativeType);
+        return rowCursor.getBoolean(columnIndex, colType);
     }
 
     @Override
     public byte getByte(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return (byte) rowCursor.getInt(columnIndex, nativeType);
+        return (byte) rowCursor.getInt(columnIndex, colType);
     }
 
     @Override
     public short getShort(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return (short) rowCursor.getInt(columnIndex, nativeType);
+        return (short) rowCursor.getInt(columnIndex, colType);
     }
 
     @Override
     public int getInt(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return rowCursor.getInt(columnIndex, nativeType);
+        return rowCursor.getInt(columnIndex, colType);
     }
 
     @Override
     public long getLong(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return rowCursor.getLong(columnIndex, nativeType);
+        return rowCursor.getLong(columnIndex, colType);
     }
 
     @Override
     public float getFloat(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return rowCursor.getFloat(columnIndex, nativeType);
+        return rowCursor.getFloat(columnIndex, colType);
     }
 
     @Override
     public double getDouble(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return rowCursor.getDouble(columnIndex, nativeType);
+        return rowCursor.getDouble(columnIndex, colType);
     }
 
     @Override
     public byte[] getBytes(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return (rowCursor.getString(columnIndex, nativeType)).getBytes();
+        return (rowCursor.getString(columnIndex, colType)).getBytes();
     }
 
     @Override
     public Timestamp getTimestamp(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        return rowCursor.getTimestamp(columnIndex, nativeType);
+        return rowCursor.getTimestamp(columnIndex, colType);
     }
 
     @Override
@@ -158,8 +148,7 @@ public class DatabaseMetaDataResultSet extends AbstractResultSet {
     @Override
     public BigDecimal getBigDecimal(int columnIndex) throws SQLException {
         int colType = columnMetaDataList.get(columnIndex - 1).getColType();
-        int nativeType = TSDBConstants.jdbcType2TaosType(colType);
-        double value = rowCursor.getDouble(columnIndex, nativeType);
+        double value = rowCursor.getDouble(columnIndex, colType);
         return new BigDecimal(value);
     }
 
diff --git a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBConstants.java b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBConstants.java
index 740e3c6c21be568bf71e4d68a3129c527da441a6..74a874513839fb076ce3f2dd9b2a6d0ecc72fb2e 100644
--- a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBConstants.java
+++ b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBConstants.java
@@ -129,8 +129,9 @@ public abstract class TSDBConstants {
                 return Types.TIMESTAMP;
             case TSDBConstants.TSDB_DATA_TYPE_NCHAR:
                 return Types.NCHAR;
+            default:
+                throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_UNKNOWN_TAOS_TYPE, "unknown taos type: " + taosType + " in tdengine");
         }
-        throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_UNKNOWN_TAOS_TYPE);
     }
 
     public static String taosType2JdbcTypeName(int taosType) throws SQLException {
@@ -160,7 +161,7 @@ public abstract class TSDBConstants {
             case TSDBConstants.TSDB_DATA_TYPE_NCHAR:
                 return "NCHAR";
             default:
-                throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_UNKNOWN_TAOS_TYPE);
+                throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_UNKNOWN_TAOS_TYPE, "unknown taos type: " + taosType + " in tdengine");
         }
     }
 
@@ -187,7 +188,7 @@ public abstract class TSDBConstants {
             case Types.NCHAR:
                 return TSDBConstants.TSDB_DATA_TYPE_NCHAR;
         }
-        throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_UNKNOWN_SQL_TYPE_IN_TDENGINE);
+        throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_UNKNOWN_SQL_TYPE_IN_TDENGINE, "unknown sql type: " + jdbcType + " in tdengine");
     }
 
     public static String jdbcType2TaosTypeName(int jdbcType) throws SQLException {
@@ -213,7 +214,7 @@ public abstract class TSDBConstants {
             case Types.NCHAR:
                 return "NCHAR";
             default:
-                throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_UNKNOWN_SQL_TYPE_IN_TDENGINE);
+                throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_UNKNOWN_SQL_TYPE_IN_TDENGINE, "unknown sql type: " + jdbcType + " in tdengine");
         }
     }
 
diff --git a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBResultSetMetaData.java b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBResultSetMetaData.java
index 6292673352529171cdc42ba73e0f47f8f05a21a4..f93384fcc7a9693c2b187498cdf0f60371d28fd0 100644
--- a/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBResultSetMetaData.java
+++ b/src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBResultSetMetaData.java
@@ -110,7 +110,7 @@ public class TSDBResultSetMetaData extends WrapperImpl implements ResultSetMetaD
 
         ColumnMetaData columnMetaData = this.colMetaDataList.get(column - 1);
         switch (columnMetaData.getColType()) {
-            
+
             case TSDBConstants.TSDB_DATA_TYPE_FLOAT:
                 return 5;
             case TSDBConstants.TSDB_DATA_TYPE_DOUBLE: