bug fixed for sql parser SchemaStatVisitor. for issue #1798

src/main/java/com/alibaba/druid/sql/dialect/db2/visitor/DB2SchemaStatVisitor.java

@@ -35,7 +35,7 @@ public class DB2SchemaStatVisitor extends SchemaStatVisitor implements DB2ASTVis
 
     @Override
     public void endVisit(DB2SelectQueryBlock x) {
-        
+        super.endVisit((SQLSelectQueryBlock) x);
     }
 
     @Override

src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlSchemaStatVisitor.java

@@ -524,7 +524,7 @@ public class MySqlSchemaStatVisitor extends SchemaStatVisitor implements MySqlAS
 
     @Override
     public void endVisit(MySqlSelectQueryBlock x) {
-
+        super.endVisit((SQLSelectQueryBlock) x);
     }
 
     @Override

src/main/java/com/alibaba/druid/sql/dialect/odps/visitor/OdpsSchemaStatVisitor.java

@@ -126,7 +126,7 @@ public class OdpsSchemaStatVisitor extends SchemaStatVisitor implements OdpsASTV
 
     @Override
     public void endVisit(OdpsSelectQueryBlock x) {
-        
+        super.endVisit((SQLSelectQueryBlock) x);
     }
 
     @Override

src/main/java/com/alibaba/druid/sql/dialect/postgresql/visitor/PGSchemaStatVisitor.java

@@ -21,6 +21,7 @@ import com.alibaba.druid.sql.ast.SQLName;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
 import com.alibaba.druid.sql.ast.statement.SQLSelectStatement;
+import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.postgresql.ast.PGWithClause;
 import com.alibaba.druid.sql.dialect.postgresql.ast.PGWithQuery;
 import com.alibaba.druid.sql.dialect.postgresql.ast.expr.PGBoxExpr;
@@ -246,7 +247,7 @@ public class PGSchemaStatVisitor extends SchemaStatVisitor implements PGASTVisit
 
     @Override
     public void endVisit(PGSelectQueryBlock x) {
-
+        super.endVisit((SQLSelectQueryBlock) x);
     }
 
     @Override