improved sql parser.

src/main/java/com/alibaba/druid/sql/ast/SQLExpr.java

@@ -17,4 +17,6 @@ package com.alibaba.druid.sql.ast;
 
 public interface SQLExpr extends SQLObject, Cloneable {
     SQLExpr clone();
+
+    SQLDataType computeDataType();
 }

src/main/java/com/alibaba/druid/sql/ast/SQLExprImpl.java

@@ -28,4 +28,8 @@ public abstract class SQLExprImpl extends SQLObjectImpl implements SQLExpr {
     public SQLExpr clone() {
         throw new UnsupportedOperationException(this.getClass().getName());
     }
+
+    public SQLDataType computeDataType() {
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/SQLObjectImpl.java

@@ -211,4 +211,8 @@ public abstract class SQLObjectImpl implements SQLObject {
     public SQLObject clone() {
         throw new UnsupportedOperationException(this.getClass().getName());
     }
+
+    public SQLDataType computeDataType() {
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLAggregateExpr.java

@@ -20,11 +20,7 @@ import java.util.ArrayList;
 import java.util.List;
 
 import com.alibaba.druid.sql.SQLUtils;
-import com.alibaba.druid.sql.ast.SQLExpr;
-import com.alibaba.druid.sql.ast.SQLExprImpl;
-import com.alibaba.druid.sql.ast.SQLKeep;
-import com.alibaba.druid.sql.ast.SQLOrderBy;
-import com.alibaba.druid.sql.ast.SQLOver;
+import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLAggregateExpr extends SQLExprImpl implements Serializable {
@@ -206,4 +202,25 @@ public class SQLAggregateExpr extends SQLExprImpl implements Serializable {
 
         return x;
     }
+
+    public SQLDataType computeDataType() {
+        if ("count".equals(methodName)
+                || "row_number".equals(methodName)) {
+            return SQLIntegerExpr.DEFAULT_DATA_TYPE;
+        }
+
+        if (arguments.size() > 0) {
+            SQLDataType dataType = arguments.get(0).computeDataType();
+            if (dataType != null) {
+                return dataType;
+            }
+        }
+
+        if ("wm_conat".equals(methodName)
+                || "group_concat".equals(methodName)) {
+            return SQLCharExpr.DEFAULT_DATA_TYPE;
+        }
+
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLAnyExpr.java

@@ -15,10 +15,15 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.ast.statement.SQLSelect;
+import com.alibaba.druid.sql.ast.statement.SQLSelectItem;
+import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
+import java.util.List;
+
 public class SQLAnyExpr extends SQLExprImpl {
 
     public SQLSelect subQuery;
@@ -82,4 +87,22 @@ public class SQLAnyExpr extends SQLExprImpl {
         }
         return true;
     }
+
+    public SQLDataType computeDataType() {
+        if (subQuery == null) {
+            return null;
+        }
+
+        SQLSelectQueryBlock queryBlock = subQuery.getFirstQueryBlock();
+        if (queryBlock == null) {
+            return null;
+        }
+
+        List<SQLSelectItem> selectList = queryBlock.getSelectList();
+        if (selectList.size() == 1) {
+            return selectList.get(0).computeDataType();
+        }
+
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLBetweenExpr.java

@@ -17,6 +17,7 @@ package com.alibaba.druid.sql.ast.expr;
 
 import java.io.Serializable;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
@@ -143,4 +144,8 @@ public class SQLBetweenExpr extends SQLExprImpl implements Serializable {
         }
         return true;
     }
+
+    public SQLDataType computeDataType() {
+        return SQLBooleanExpr.DEFAULT_DATA_TYPE;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLBinaryOpExpr.java

@@ -20,10 +20,7 @@ import java.util.ArrayList;
 import java.util.List;
 
 import com.alibaba.druid.sql.SQLUtils;
-import com.alibaba.druid.sql.ast.SQLExpr;
-import com.alibaba.druid.sql.ast.SQLExprImpl;
-import com.alibaba.druid.sql.ast.SQLObject;
-import com.alibaba.druid.sql.ast.SQLReplaceable;
+import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 import com.alibaba.druid.util.Utils;
 
@@ -429,4 +426,30 @@ public class SQLBinaryOpExpr extends SQLExprImpl implements SQLReplaceable, Seri
 
         return false;
     }
+
+    public SQLDataType computeDataType() {
+        if (operator != null && operator.isRelational()) {
+            return SQLBooleanExpr.DEFAULT_DATA_TYPE;
+        }
+
+        SQLDataType leftDataType = null, rightDataType = null;
+        if (left != null) {
+            leftDataType = left.computeDataType();
+        }
+        if (right != null) {
+            rightDataType = right.computeDataType();
+        }
+
+        if (operator == SQLBinaryOperator.Concat) {
+            if (leftDataType != null) {
+                return leftDataType;
+            }
+            if (rightDataType != null) {
+                return rightDataType;
+            }
+            return SQLCharExpr.DEFAULT_DATA_TYPE;
+        }
+
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLBinaryOperator.java

@@ -138,6 +138,8 @@ public enum SQLBinaryOperator {
             case NotRLike:
             case RegExp:
             case NotRegExp:
+            case Is:
+            case IsNot:
                 return true;
             default:
                 return false;

src/main/java/com/alibaba/druid/sql/ast/expr/SQLBooleanExpr.java

@@ -15,11 +15,14 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
+import com.alibaba.druid.sql.ast.statement.SQLCharacterDataType;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLBooleanExpr extends SQLExprImpl implements SQLExpr, SQLLiteralExpr {
+    public static final SQLDataType DEFAULT_DATA_TYPE = new SQLCharacterDataType("boolean");
 
     private boolean value;
 
@@ -77,4 +80,7 @@ public class SQLBooleanExpr extends SQLExprImpl implements SQLExpr, SQLLiteralEx
         return true;
     }
 
+    public SQLDataType computeDataType() {
+        return DEFAULT_DATA_TYPE;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLCaseExpr.java

@@ -19,10 +19,7 @@ import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.List;
 
-import com.alibaba.druid.sql.ast.SQLExpr;
-import com.alibaba.druid.sql.ast.SQLExprImpl;
-import com.alibaba.druid.sql.ast.SQLObjectImpl;
-import com.alibaba.druid.sql.ast.SQLReplaceable;
+import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLCaseExpr extends SQLExprImpl implements SQLReplaceable, Serializable {
@@ -255,4 +252,22 @@ public class SQLCaseExpr extends SQLExprImpl implements SQLReplaceable, Serializ
 
         return x;
     }
+
+    public SQLDataType computeDataType() {
+        for (Item item : items) {
+            SQLExpr expr = item.getValueExpr();
+            if (expr != null) {
+                SQLDataType dataType = expr.computeDataType();
+                if (dataType != null) {
+                    return dataType;
+                }
+            }
+        }
+
+        if(elseExpr != null) {
+            return elseExpr.computeDataType();
+        }
+
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLCastExpr.java

@@ -94,4 +94,7 @@ public class SQLCastExpr extends SQLExprImpl {
         return true;
     }
 
+    public SQLDataType computeDataType() {
+        return dataType;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLCharExpr.java

@@ -16,10 +16,13 @@
 package com.alibaba.druid.sql.ast.expr;
 
 import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLDataType;
+import com.alibaba.druid.sql.ast.statement.SQLCharacterDataType;
 import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLCharExpr extends SQLTextLiteralExpr implements SQLValuableExpr{
+    public static final SQLDataType DEFAULT_DATA_TYPE = new SQLCharacterDataType("varchar");
 
     public SQLCharExpr(){
 
@@ -55,4 +58,8 @@ public class SQLCharExpr extends SQLTextLiteralExpr implements SQLValuableExpr{
     public SQLCharExpr clone() {
         return new SQLCharExpr(this.text);
     }
+
+    public SQLDataType computeDataType() {
+        return DEFAULT_DATA_TYPE;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLDateExpr.java

@@ -15,12 +15,15 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
+import com.alibaba.druid.sql.ast.statement.SQLCharacterDataType;
 import com.alibaba.druid.sql.dialect.oracle.ast.expr.OracleExpr;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLDateExpr extends SQLExprImpl implements SQLLiteralExpr {
+    public static final SQLDataType DEFAULT_DATA_TYPE = new SQLCharacterDataType("date");
 
     private String literal;
 

src/main/java/com/alibaba/druid/sql/ast/expr/SQLIdentifierExpr.java

@@ -16,6 +16,7 @@
 package com.alibaba.druid.sql.ast.expr;
 
 import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.ast.SQLName;
 import com.alibaba.druid.sql.ast.statement.SQLColumnDefinition;
@@ -147,4 +148,12 @@ public class SQLIdentifierExpr extends SQLExprImpl implements SQLName {
     public void setResolvedColumn(SQLColumnDefinition resolvedColumn) {
         this.resolvedColumn = resolvedColumn;
     }
+
+    public SQLDataType computeDataType() {
+        if (resolvedColumn != null) {
+            return resolvedColumn.getDataType();
+        }
+
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLInListExpr.java

@@ -19,6 +19,7 @@ import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
@@ -121,4 +122,8 @@ public class SQLInListExpr extends SQLExprImpl implements Serializable {
         }
         return true;
     }
+
+    public SQLDataType computeDataType() {
+        return SQLBooleanExpr.DEFAULT_DATA_TYPE;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLInSubQueryExpr.java

@@ -17,6 +17,7 @@ package com.alibaba.druid.sql.ast.expr;
 
 import java.io.Serializable;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.ast.statement.SQLSelect;
@@ -125,4 +126,7 @@ public class SQLInSubQueryExpr extends SQLExprImpl implements Serializable {
         return true;
     }
 
+    public SQLDataType computeDataType() {
+        return SQLBooleanExpr.DEFAULT_DATA_TYPE;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLIntegerExpr.java

@@ -15,9 +15,12 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
+import com.alibaba.druid.sql.ast.SQLDataTypeImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLIntegerExpr extends SQLNumericLiteralExpr implements SQLValuableExpr{
+    public static final SQLDataType DEFAULT_DATA_TYPE = new SQLDataTypeImpl("bigint");
 
     private Number number;
 
@@ -86,4 +89,8 @@ public class SQLIntegerExpr extends SQLNumericLiteralExpr implements SQLValuable
     public SQLIntegerExpr clone() {
         return new SQLIntegerExpr(this.number);
     }
+
+    public SQLDataType computeDataType() {
+        return DEFAULT_DATA_TYPE;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLNCharExpr.java

@@ -15,9 +15,12 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
+import com.alibaba.druid.sql.ast.statement.SQLCharacterDataType;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLNCharExpr extends SQLTextLiteralExpr {
+    private static SQLDataType defaultDataType = new SQLCharacterDataType("nvarchar");
 
     public SQLNCharExpr(){
 
@@ -46,4 +49,8 @@ public class SQLNCharExpr extends SQLTextLiteralExpr {
     public SQLNCharExpr clone() {
         return new SQLNCharExpr(text);
     }
+
+    public SQLDataType computeDataType() {
+        return defaultDataType;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLNotExpr.java

@@ -17,6 +17,7 @@ package com.alibaba.druid.sql.ast.expr;
 
 import java.io.Serializable;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
@@ -94,4 +95,8 @@ public class SQLNotExpr extends SQLExprImpl implements Serializable {
         }
         return x;
     }
+
+    public SQLDataType computeDataType() {
+        return SQLBooleanExpr.DEFAULT_DATA_TYPE;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLNumberExpr.java

@@ -15,9 +15,12 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
+import com.alibaba.druid.sql.ast.SQLDataTypeImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLNumberExpr extends SQLNumericLiteralExpr {
+    private static SQLDataType defaultDataType = new SQLDataTypeImpl("number");
 
     private Number number;
 
@@ -80,4 +83,8 @@ public class SQLNumberExpr extends SQLNumericLiteralExpr {
     public SQLNumberExpr clone() {
         return new SQLNumberExpr(number);
     }
+
+    public SQLDataType computeDataType() {
+        return defaultDataType;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLPropertyExpr.java

@@ -16,6 +16,7 @@
 package com.alibaba.druid.sql.ast.expr;
 
 import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.ast.SQLName;
@@ -164,4 +165,12 @@ public class SQLPropertyExpr extends SQLExprImpl implements SQLName {
     public void setResolvedColumn(SQLColumnDefinition resolvedColumn) {
         this.resolvedColumn = resolvedColumn;
     }
+
+    public SQLDataType computeDataType() {
+        if (resolvedColumn != null) {
+            return resolvedColumn.getDataType();
+        }
+
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLQueryExpr.java

@@ -16,9 +16,13 @@
 package com.alibaba.druid.sql.ast.expr;
 
 import java.io.Serializable;
+import java.util.List;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.ast.statement.SQLSelect;
+import com.alibaba.druid.sql.ast.statement.SQLSelectItem;
+import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLQueryExpr extends SQLExprImpl implements Serializable {
@@ -97,4 +101,22 @@ public class SQLQueryExpr extends SQLExprImpl implements Serializable {
 
         return x;
     }
+
+    public SQLDataType computeDataType() {
+        if (subQuery == null) {
+            return null;
+        }
+
+        SQLSelectQueryBlock queryBlock = subQuery.getFirstQueryBlock();
+        if (queryBlock == null) {
+            return null;
+        }
+
+        List<SQLSelectItem> selectList = queryBlock.getSelectList();
+        if (selectList.size() == 1) {
+            return selectList.get(0).computeDataType();
+        }
+
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLSomeExpr.java

@@ -15,10 +15,15 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.ast.statement.SQLSelect;
+import com.alibaba.druid.sql.ast.statement.SQLSelectItem;
+import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
+import java.util.List;
+
 public class SQLSomeExpr extends SQLExprImpl {
 
     public SQLSelect subQuery;
@@ -82,4 +87,22 @@ public class SQLSomeExpr extends SQLExprImpl {
         }
         return true;
     }
+
+    public SQLDataType computeDataType() {
+        if (subQuery == null) {
+            return null;
+        }
+
+        SQLSelectQueryBlock queryBlock = subQuery.getFirstQueryBlock();
+        if (queryBlock == null) {
+            return null;
+        }
+
+        List<SQLSelectItem> selectList = queryBlock.getSelectList();
+        if (selectList.size() == 1) {
+            return selectList.get(0).computeDataType();
+        }
+
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLTimestampExpr.java

@@ -1,7 +1,9 @@
 package com.alibaba.druid.sql.ast.expr;
 
 import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
+import com.alibaba.druid.sql.ast.statement.SQLCharacterDataType;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 /*
@@ -20,6 +22,7 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
  * limitations under the License.
  */
 public class SQLTimestampExpr extends SQLExprImpl {
+    public static final SQLDataType DEFAULT_DATA_TYPE = new SQLCharacterDataType("datetime");
 
     protected String  literal;
     protected String  timeZone;
@@ -105,4 +108,8 @@ public class SQLTimestampExpr extends SQLExprImpl {
     public String toString() {
         return SQLUtils.toSQLString(this, null);
     }
+
+    public SQLDataType computeDataType() {
+        return DEFAULT_DATA_TYPE;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLExprTableSource.java

@@ -21,6 +21,7 @@ import java.util.List;
 import com.alibaba.druid.sql.SQLUtils;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLName;
+import com.alibaba.druid.sql.ast.SQLStatement;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.expr.SQLPropertyExpr;
 import com.alibaba.druid.sql.repository.SchemaObject;
@@ -171,4 +172,17 @@ public class SQLExprTableSource extends SQLTableSourceImpl {
 
         return false;
     }
+
+    public SQLColumnDefinition findColumn(String columnName) {
+        if (schemaObject == null) {
+            return null;
+        }
+
+        SQLStatement stmt = schemaObject.getStatement();
+        if (stmt instanceof SQLCreateTableStatement) {
+            SQLCreateTableStatement createTableStmt = (SQLCreateTableStatement) stmt;
+            return createTableStmt.findColumn(columnName);
+        }
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLJoinTableSource.java

@@ -21,6 +21,7 @@ import java.util.List;
 import com.alibaba.druid.sql.SQLUtils;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLReplaceable;
+import com.alibaba.druid.sql.ast.SQLStatement;
 import com.alibaba.druid.sql.ast.expr.SQLBinaryOpExpr;
 import com.alibaba.druid.sql.ast.expr.SQLBinaryOperator;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
@@ -368,4 +369,19 @@ public class SQLJoinTableSource extends SQLTableSourceImpl implements SQLReplace
         return false;
     }
 
+    public SQLColumnDefinition findColumn(String columnName) {
+        if (left != null) {
+            SQLColumnDefinition column = left.findColumn(columnName);
+            if (column != null) {
+                return column;
+            }
+        }
+
+        if (right != null) {
+            return right.findColumn(columnName);
+        }
+
+        return null;
+    }
+
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLSelect.java

@@ -272,4 +272,15 @@ public class SQLSelect extends SQLObjectImpl {
         this.xmlPath = xmlPath;
     }
 
+    public SQLSelectQueryBlock getFirstQueryBlock() {
+        if (query instanceof SQLSelectQueryBlock) {
+            return (SQLSelectQueryBlock) query;
+        }
+
+        if (query instanceof SQLUnionQuery) {
+            return ((SQLUnionQuery) query).getFirstQueryBlock();
+        }
+
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLSelectItem.java

@@ -82,23 +82,11 @@ public class SQLSelectItem extends SQLObjectImpl implements SQLReplaceable {
     }
 
     public SQLDataType computeDataType() {
-        if (expr instanceof SQLIdentifierExpr) {
-            SQLIdentifierExpr identExpr = (SQLIdentifierExpr) expr;
-            if (identExpr.getResolvedColumn() != null) {
-                return identExpr.getResolvedColumn().getDataType();
-            }
+        if (expr == null) {
             return null;
         }
 
-        if (expr instanceof SQLPropertyExpr) {
-            SQLPropertyExpr propertyExpr = (SQLPropertyExpr) expr;
-            if (propertyExpr.getResolvedColumn() != null) {
-                return propertyExpr.getResolvedColumn().getDataType();
-            }
-            return null;
-        }
-
-        return null;
+        return expr.computeDataType();
     }
 
     public String getAlias() {

src/main/java/com/alibaba/druid/sql/ast/statement/SQLSelectQueryBlock.java

@@ -23,6 +23,7 @@ import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.ast.expr.SQLBinaryOpExpr;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.expr.SQLIntegerExpr;
+import com.alibaba.druid.sql.repository.SchemaObject;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery, SQLReplaceable {
@@ -533,4 +534,18 @@ public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery
 
         return -1;
     }
+
+    public SQLColumnDefinition computeColumn(SQLIdentifierExpr identExpr) {
+        SQLColumnDefinition column = identExpr.getResolvedColumn();
+        if (column != null) {
+            return column;
+        }
+
+        column = from.findColumn(identExpr.getName());
+        if (column != null) {
+            identExpr.setResolvedColumn(column);
+        }
+
+        return column;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLTableSource.java

@@ -36,4 +36,6 @@ public interface SQLTableSource extends SQLObject {
 
     SQLExpr getFlashback();
     void setFlashback(SQLExpr flashback);
+
+    SQLColumnDefinition findColumn(String columnName);
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLTableSourceImpl.java

@@ -94,4 +94,8 @@ public abstract class SQLTableSourceImpl extends SQLObjectImpl implements SQLTab
 
         return false;
     }
+
+    public SQLColumnDefinition findColumn(String columnName) {
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/OracleSQLObjectImpl.java

@@ -15,6 +15,7 @@
  */
 package com.alibaba.druid.sql.dialect.oracle.ast;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLObjectImpl;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
@@ -36,4 +37,8 @@ public abstract class OracleSQLObjectImpl extends SQLObjectImpl implements Oracl
     public OracleSQLObject clone() {
         throw new UnsupportedOperationException();
     }
+
+    public SQLDataType computeDataType() {
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/expr/OracleAnalytic.java

@@ -15,6 +15,7 @@
  */
 package com.alibaba.druid.sql.dialect.oracle.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLOver;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
@@ -60,4 +61,8 @@ public class OracleAnalytic extends SQLOver implements OracleExpr {
     public void setWindowing(OracleAnalyticWindowing windowing) {
         this.windowing = windowing;
     }
+
+    public SQLDataType computeDataType() {
+        return null;
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/expr/OracleTreatExpr.java

@@ -15,6 +15,7 @@
  */
 package com.alibaba.druid.sql.dialect.oracle.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleSQLObjectImpl;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;

src/main/java/com/alibaba/druid/sql/repository/Schema.java

@@ -196,14 +196,7 @@ public class Schema {
             select.accept(
                     repository.createResolveVisitor());
 
-            SQLSelectQuery query = select.getQuery();
-            SQLSelectQueryBlock queryBlock = null;
-            if (query instanceof SQLSelectQueryBlock) {
-                queryBlock = (SQLSelectQueryBlock) query;
-            } else if (query instanceof SQLUnionQuery) {
-                queryBlock = ((SQLUnionQuery) query).getFirstQueryBlock();
-            }
-            
+            SQLSelectQueryBlock queryBlock = select.getFirstQueryBlock();
             if (queryBlock != null) {
                 List<SQLSelectItem> selectList = queryBlock.getSelectList();
                 for (SQLSelectItem selectItem : selectList) {

src/main/java/com/alibaba/druid/sql/repository/SchemaRepository.java

@@ -266,32 +266,69 @@ public class SchemaRepository {
 
     public class MySqlResolveVisitor extends MySqlASTVisitorAdapter {
 
+        public boolean visit(SQLExprTableSource x) {
+            if (x.getSchemaObject() != null) {
+                return false;
+            }
+
+            SQLExpr expr = x.getExpr();
+            if (expr instanceof SQLName) {
+                SchemaObject table = findTable((SQLName) expr);
+                if (table != null) {
+                    x.setSchemaObject(table);
+                }
+            }
+            return false;
+        }
+
         public boolean visit(MySqlSelectQueryBlock x) {
+            SQLTableSource from = x.getFrom();
+            from.accept(this);
+
             List<SQLSelectItem> selectList = x.getSelectList();
+
+            List<SQLSelectItem> columns = new ArrayList<SQLSelectItem>();
             for (int i = selectList.size() - 1; i >= 0; i--) {
                 SQLSelectItem selectItem = selectList.get(i);
                 SQLExpr expr = selectItem.getExpr();
                 if (expr instanceof SQLAllColumnExpr) {
-                    SQLTableSource from = x.getFrom();
-                    List<SQLSelectItem> columns = new ArrayList<SQLSelectItem>();
-                    if (from instanceof SQLExprTableSource) {
-                        SchemaObject table = findTable((SQLExprTableSource) from);
-                        if (table != null) {
-                            SQLCreateTableStatement createTableStmt = (SQLCreateTableStatement) table.getStatement();
-                            for (SQLTableElement e : createTableStmt.getTableElementList()) {
-                                if (e instanceof SQLColumnDefinition) {
-                                    SQLColumnDefinition column = (SQLColumnDefinition) e;
-                                    SQLIdentifierExpr name = (SQLIdentifierExpr) column.getName().clone();
-                                    name.setResolvedColumn(column);
-                                    columns.add(new SQLSelectItem(name));
-                                }
-                            }
-                        }
+                    extractColumns(from, columns);
+                } else if (expr instanceof SQLPropertyExpr) {
+                    SQLPropertyExpr propertyExpr = (SQLPropertyExpr) expr;
+                    String ownerName = propertyExpr.getOwnernName();
+                    if (propertyExpr.getName().equals("*")) {
+                        SQLTableSource tableSource = x.findTableSource(ownerName);
+                        extractColumns(tableSource, columns);
                     }
 
+                    SQLColumnDefinition column = propertyExpr.getResolvedColumn();
+                    if (column != null) {
+                        continue;
+                    }
+                    SQLTableSource tableSource = x.findTableSource(propertyExpr.getOwnernName());
+                    if (tableSource != null) {
+                        column = tableSource.findColumn(propertyExpr.getName());
+                        if (column != null) {
+                            propertyExpr.setResolvedColumn(column);
+                        }
+                    }
+                } else if (expr instanceof SQLIdentifierExpr) {
+                    SQLIdentifierExpr identExpr = (SQLIdentifierExpr) expr;
+                    SQLColumnDefinition column = identExpr.getResolvedColumn();
+                    if (column != null) {
+                        continue;
+                    }
+                    column = from.findColumn(identExpr.getName());
+                    if (column != null) {
+                        identExpr.setResolvedColumn(column);
+                    }
+                }
+
+                if (columns.size() > 0) {
                     for (SQLSelectItem column : columns) {
                         column.setParent(x);
                     }
+
                     selectList.remove(i);
                     selectList.addAll(i, columns);
                 }
@@ -301,6 +338,23 @@ public class SchemaRepository {
         }
     }
 
+    private void extractColumns(SQLTableSource from, List<SQLSelectItem> columns) {
+        if (from instanceof SQLExprTableSource) {
+            SchemaObject table = findTable((SQLExprTableSource) from);
+            if (table != null) {
+                SQLCreateTableStatement createTableStmt = (SQLCreateTableStatement) table.getStatement();
+                for (SQLTableElement e : createTableStmt.getTableElementList()) {
+                    if (e instanceof SQLColumnDefinition) {
+                        SQLColumnDefinition column = (SQLColumnDefinition) e;
+                        SQLIdentifierExpr name = (SQLIdentifierExpr) column.getName().clone();
+                        name.setResolvedColumn(column);
+                        columns.add(new SQLSelectItem(name));
+                    }
+                }
+            }
+        }
+    }
+
     public SchemaObject findTable(SQLExprTableSource x) {
         if (x == null) {
             return null;