diff --git a/src/main/java/com/alibaba/druid/common/jdbc/ResultSetMetaDataBase.java b/src/main/java/com/alibaba/druid/common/jdbc/ResultSetMetaDataBase.java
index 627fff312a..b1f89a1cb8 100644
--- a/src/main/java/com/alibaba/druid/common/jdbc/ResultSetMetaDataBase.java
+++ b/src/main/java/com/alibaba/druid/common/jdbc/ResultSetMetaDataBase.java
@@ -35,11 +35,7 @@ public class ResultSetMetaDataBase implements ResultSetMetaData {
     @SuppressWarnings("unchecked")
     @Override
     public <T> T unwrap(Class<T> iface) throws SQLException {
-        if (iface == null) {
-            return null;
-        }
-
-        if (iface.isAssignableFrom(ResultSetMetaDataBase.class)) {
+        if (isWrapperFor(iface)) {
             return (T) this;
         }
         return null;
@@ -50,8 +46,12 @@ public class ResultSetMetaDataBase implements ResultSetMetaData {
         if (iface == null) {
             return false;
         }
+        
+        if (iface.isAssignableFrom(this.getClass())) {
+            return true;
+        }
 
-        return ResultSetMetaDataBase.class.isAssignableFrom(iface);
+        return false;
     }
 
     @Override
diff --git a/src/main/java/com/alibaba/druid/common/jdbc/StatementBase.java b/src/main/java/com/alibaba/druid/common/jdbc/StatementBase.java
index 351e7ca8f1..05676e39d2 100644
--- a/src/main/java/com/alibaba/druid/common/jdbc/StatementBase.java
+++ b/src/main/java/com/alibaba/druid/common/jdbc/StatementBase.java
@@ -7,6 +7,8 @@ import java.sql.SQLFeatureNotSupportedException;
 import java.sql.SQLWarning;
 import java.sql.Statement;
 
+import com.alibaba.druid.mock.MockConnectionClosedException;
+
 public abstract class StatementBase implements Statement {
 
     private Connection connection;
@@ -41,8 +43,14 @@ public abstract class StatementBase implements Statement {
         this.connection = connection;
     }
 
-    protected void checkOpen() throws SQLException {
-
+    protected void checkOpen() throws SQLException, MockConnectionClosedException {
+        if (closed) {
+            throw new SQLException();
+        }
+        
+        if (this.connection != null && this.connection.isClosed()) {
+            throw new MockConnectionClosedException();
+        }
     }
 
     @Override
@@ -198,11 +206,7 @@ public abstract class StatementBase implements Statement {
     @SuppressWarnings("unchecked")
     @Override
     public <T> T unwrap(Class<T> iface) throws SQLException {
-        if (iface == null) {
-            return null;
-        }
-
-        if (iface.isInstance(this)) {
+        if (isWrapperFor(iface)) {
             return (T) this;
         }
 
@@ -215,7 +219,7 @@ public abstract class StatementBase implements Statement {
             return false;
         }
 
-        if (iface.isInstance(this)) {
+        if (iface == this.getClass() || iface.isInstance(this)) {
             return true;
         }
 
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveCreateTableParser.java b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveCreateTableParser.java
index 52116b6843..76d309855a 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveCreateTableParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveCreateTableParser.java
@@ -24,7 +24,7 @@ public class HiveCreateTableParser extends SQLCreateTableParser {
     public SQLCreateTableStatement parseCrateTable(boolean acceptCreate) {
         HiveCreateTableStatement stmt = (HiveCreateTableStatement) super.parseCrateTable(acceptCreate);
 
-        if (lexer.token() == Token.PARTITIONED) {
+        if (identifierEquals("PARTITIONED")) {
             lexer.nextToken();
             accept(Token.BY);
             accept(Token.LPAREN);
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveExprParser.java b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveExprParser.java
new file mode 100644
index 0000000000..c297327b75
--- /dev/null
+++ b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveExprParser.java
@@ -0,0 +1,17 @@
+package com.alibaba.druid.sql.dialect.hive.parser;
+
+import com.alibaba.druid.sql.parser.Lexer;
+import com.alibaba.druid.sql.parser.ParserException;
+import com.alibaba.druid.sql.parser.SQLExprParser;
+
+
+public class HiveExprParser extends SQLExprParser {
+    public HiveExprParser(String sql) throws ParserException{
+        super(new HiveLexer(sql));
+        this.lexer.nextToken();
+    }
+
+    public HiveExprParser(Lexer lexer){
+        super(lexer);
+    }
+}
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveLexer.java b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveLexer.java
index 73fddd3ecf..ee74a8ec4e 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveLexer.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveLexer.java
@@ -83,9 +83,6 @@ public class HiveLexer extends Lexer {
         map.put("ANY", Token.ANY);
 
         map.put("WITH", Token.WITH);
-        map.put("PARTITIONED", Token.PARTITIONED);
-        map.put("SHOW", Token.SHOW);
-        map.put("TABLES", Token.TABLES);
 
         DEFAULT_SQL_SERVER_KEYWORDS = new Keywords(map);
     }
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveStatementParser.java b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveStatementParser.java
index fa7da28e04..80a60873a8 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveStatementParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveStatementParser.java
@@ -25,10 +25,10 @@ public class HiveStatementParser extends SQLStatementParser {
     }
 
     public boolean parseStatementListDialect(List<SQLStatement> statementList) {
-        if (lexer.token() == Token.SHOW) {
+        if (identifierEquals("SHOW")) {
             lexer.nextToken();
 
-            if (lexer.token() == Token.TABLES) {
+            if (identifierEquals("TABLES")) {
                 lexer.nextToken();
 
                 HiveShowTablesStatement stmt = new HiveShowTablesStatement();
@@ -41,7 +41,7 @@ public class HiveStatementParser extends SQLStatementParser {
                 return true;
             }
 
-            throw new ParserException("TODO " + lexer.token());
+            throw new ParserException("TODO " + lexer.info());
         }
         return false;
     }
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGExprParser.java b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGExprParser.java
index 0e7f8017e6..4d4ec91164 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGExprParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGExprParser.java
@@ -11,7 +11,8 @@ import com.alibaba.druid.sql.parser.Token;
 
 public class PGExprParser extends SQLExprParser{
     public PGExprParser(String sql) throws ParserException{
-        super(sql);
+        super(new PGLexer(sql));
+        this.lexer.nextToken();
     }
 
     public PGExprParser(Lexer lexer){
diff --git a/src/main/java/com/alibaba/druid/sql/parser/Lexer.java b/src/main/java/com/alibaba/druid/sql/parser/Lexer.java
index 99ec0915d0..e0804ab0b2 100644
--- a/src/main/java/com/alibaba/druid/sql/parser/Lexer.java
+++ b/src/main/java/com/alibaba/druid/sql/parser/Lexer.java
@@ -185,6 +185,10 @@ public class Lexer {
     public final Token token() {
         return token;
     }
+    
+    public String info() {
+        return this.token + " " + this.stringVal();
+    }
 
     public final void nextToken() {
         sp = 0;
diff --git a/src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java b/src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java
index ee674125d0..3301429bfa 100644
--- a/src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java
+++ b/src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java
@@ -184,6 +184,13 @@ public class SQLStatementParser extends SQLParser {
                 statementList.add(stmt);
                 continue;
             }
+            
+            if (identifierEquals("COMMIT")) {
+                SQLStatement stmt = parseCommit();
+                
+                statementList.add(stmt);
+                continue;
+            }
 
             if (lexer.token() == Token.LPAREN) {
                 char mark_ch = lexer.current();
@@ -225,6 +232,10 @@ public class SQLStatementParser extends SQLParser {
         }
         return stmt;
     }
+    
+    public SQLStatement parseCommit() {
+        throw new ParserException("TODO " + lexer.token() + " " + lexer.stringVal());
+    }
 
     public SQLUseStatement parseUse() {
         accept(Token.USE);
diff --git a/src/main/java/com/alibaba/druid/sql/parser/Token.java b/src/main/java/com/alibaba/druid/sql/parser/Token.java
index 3173dfb66a..1569f27b38 100644
--- a/src/main/java/com/alibaba/druid/sql/parser/Token.java
+++ b/src/main/java/com/alibaba/druid/sql/parser/Token.java
@@ -167,9 +167,6 @@ public enum Token {
     TOP("TOP"),
     
     // hive
-    PARTITIONED("PARTITIONED"),
-    SHOW("SHOW"),
-    TABLES("TABLES"),
 
     EOF, 
     ERROR,
diff --git a/src/test/java/com/alibaba/druid/bvt/bug/Bug_for_happyday517.java b/src/test/java/com/alibaba/druid/bvt/bug/Bug_for_happyday517.java
index 8ae1f37dd0..868f8bd9d6 100644
--- a/src/test/java/com/alibaba/druid/bvt/bug/Bug_for_happyday517.java
+++ b/src/test/java/com/alibaba/druid/bvt/bug/Bug_for_happyday517.java
@@ -8,6 +8,7 @@ import junit.framework.Assert;
 import junit.framework.TestCase;
 
 import com.alibaba.druid.mock.MockDriver;
+import com.alibaba.druid.mock.MockPreparedStatement;
 import com.alibaba.druid.mock.MockStatement;
 import com.alibaba.druid.pool.DruidDataSource;
 import com.alibaba.druid.stat.DruidDataSourceStatManager;
@@ -68,7 +69,7 @@ public class Bug_for_happyday517 extends TestCase {
         String sql = "select 1";
         Statement stmt = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
 
-        MockStatement mockStmt = stmt.unwrap(MockStatement.class);
+        MockPreparedStatement mockStmt = stmt.unwrap(MockPreparedStatement.class);
 
         Assert.assertEquals(ResultSet.TYPE_SCROLL_SENSITIVE, mockStmt.getResultSetType());
         Assert.assertEquals(ResultSet.CONCUR_UPDATABLE, mockStmt.getResultSetConcurrency());
@@ -85,7 +86,7 @@ public class Bug_for_happyday517 extends TestCase {
         Statement stmt = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE,
                                                ResultSet.CLOSE_CURSORS_AT_COMMIT);
 
-        MockStatement mockStmt = stmt.unwrap(MockStatement.class);
+        MockPreparedStatement mockStmt = stmt.unwrap(MockPreparedStatement.class);
 
         Assert.assertEquals(ResultSet.TYPE_SCROLL_SENSITIVE, mockStmt.getResultSetType());
         Assert.assertEquals(ResultSet.CONCUR_UPDATABLE, mockStmt.getResultSetConcurrency());
@@ -102,7 +103,7 @@ public class Bug_for_happyday517 extends TestCase {
         String sql = "select 1";
         Statement stmt = conn.prepareCall(sql, ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
 
-        MockStatement mockStmt = stmt.unwrap(MockStatement.class);
+        Statement mockStmt = stmt.unwrap(Statement.class);
 
         Assert.assertEquals(ResultSet.TYPE_SCROLL_SENSITIVE, mockStmt.getResultSetType());
         Assert.assertEquals(ResultSet.CONCUR_UPDATABLE, mockStmt.getResultSetConcurrency());
@@ -119,7 +120,7 @@ public class Bug_for_happyday517 extends TestCase {
         Statement stmt = conn.prepareCall(sql, ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE,
                                           ResultSet.CLOSE_CURSORS_AT_COMMIT);
 
-        MockStatement mockStmt = stmt.unwrap(MockStatement.class);
+        Statement mockStmt = stmt.unwrap(Statement.class);
 
         Assert.assertEquals(ResultSet.TYPE_SCROLL_SENSITIVE, mockStmt.getResultSetType());
         Assert.assertEquals(ResultSet.CONCUR_UPDATABLE, mockStmt.getResultSetConcurrency());
diff --git a/src/test/java/com/alibaba/druid/bvt/mock/MockResultSetMetaDataTest.java b/src/test/java/com/alibaba/druid/bvt/mock/MockResultSetMetaDataTest.java
index aa78e1c195..1636b25e7e 100644
--- a/src/test/java/com/alibaba/druid/bvt/mock/MockResultSetMetaDataTest.java
+++ b/src/test/java/com/alibaba/druid/bvt/mock/MockResultSetMetaDataTest.java
@@ -2,11 +2,13 @@ package com.alibaba.druid.bvt.mock;
 
 import java.math.BigDecimal;
 import java.sql.Date;
+import java.sql.ResultSetMetaData;
 
 import junit.framework.TestCase;
 
 import org.junit.Assert;
 
+import com.alibaba.druid.common.jdbc.ResultSetMetaDataBase;
 import com.alibaba.druid.common.jdbc.ResultSetMetaDataBase.ColumnMetaData;
 import com.alibaba.druid.mock.MockResultSetMetaData;
 
@@ -17,6 +19,8 @@ public class MockResultSetMetaDataTest extends TestCase {
         Assert.assertTrue(meta.isWrapperFor(MockResultSetMetaData.class));
         Assert.assertFalse(meta.isWrapperFor(BigDecimal.class));
         Assert.assertTrue(meta.unwrap(MockResultSetMetaData.class) instanceof MockResultSetMetaData);
+        Assert.assertTrue(meta.unwrap(ResultSetMetaDataBase.class) instanceof MockResultSetMetaData);
+        Assert.assertTrue(meta.unwrap(ResultSetMetaData.class) instanceof MockResultSetMetaData);
         Assert.assertTrue(meta.unwrap(null) == null);
         Assert.assertTrue(meta.unwrap(java.sql.ResultSetMetaData.class) != null);
         Assert.assertTrue(meta.unwrap(Object.class) != null);
diff --git a/src/test/java/com/alibaba/druid/bvt/pool/Case3.java b/src/test/java/com/alibaba/druid/bvt/pool/Case3.java
index 50b7f069da..7036a7061e 100644
--- a/src/test/java/com/alibaba/druid/bvt/pool/Case3.java
+++ b/src/test/java/com/alibaba/druid/bvt/pool/Case3.java
@@ -4,11 +4,11 @@ import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.sql.Statement;
 
 import junit.framework.Assert;
 import junit.framework.TestCase;
 
-import com.alibaba.druid.mock.MockStatement;
 import com.alibaba.druid.pool.DruidDataSource;
 import com.alibaba.druid.stat.DruidDataSourceStatManager;
 
@@ -59,7 +59,7 @@ public class Case3 extends TestCase {
         ResultSet rs = stmt.executeQuery();
         rs.next();
 
-        MockStatement mockStmt = stmt.unwrap(MockStatement.class);
+        Statement mockStmt = stmt.unwrap(Statement.class);
         Assert.assertEquals(false, mockStmt.isClosed());
 
         conn.close();
diff --git a/src/test/java/com/alibaba/druid/bvt/pool/TestOraclePrefetch.java b/src/test/java/com/alibaba/druid/bvt/pool/TestOraclePrefetch.java
index 47a6cbbe90..43c8b7e3d1 100644
--- a/src/test/java/com/alibaba/druid/bvt/pool/TestOraclePrefetch.java
+++ b/src/test/java/com/alibaba/druid/bvt/pool/TestOraclePrefetch.java
@@ -80,6 +80,5 @@ public class TestOraclePrefetch extends TestCase {
             conn.close();
         }
 
-        dataSource.close();
     }
 }
diff --git a/src/test/java/com/alibaba/druid/bvt/sql/hive/HiveShowTableTest.java b/src/test/java/com/alibaba/druid/bvt/sql/hive/HiveShowTableTest.java
index 8a41f2df08..f4e06c9143 100644
--- a/src/test/java/com/alibaba/druid/bvt/sql/hive/HiveShowTableTest.java
+++ b/src/test/java/com/alibaba/druid/bvt/sql/hive/HiveShowTableTest.java
@@ -8,7 +8,6 @@ import com.alibaba.druid.sql.ast.SQLStatement;
 import com.alibaba.druid.sql.dialect.hive.parser.HiveStatementParser;
 import com.alibaba.druid.sql.dialect.hive.visitor.HiveSchemaStatVisitor;
 import com.alibaba.druid.sql.hive.HiveTest;
-import com.alibaba.druid.stat.TableStat;
 
 public class HiveShowTableTest extends HiveTest {