improved odps sql formatter

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

@@ -16,11 +16,11 @@
 package com.alibaba.druid.sql.ast.statement;
 
 import com.alibaba.druid.sql.ast.SQLExpr;
-import com.alibaba.druid.sql.ast.SQLObjectImpl;
 import com.alibaba.druid.sql.ast.SQLStatement;
+import com.alibaba.druid.sql.ast.SQLStatementImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class SQLCommentStatement extends SQLObjectImpl implements SQLStatement {
+public class SQLCommentStatement extends SQLStatementImpl implements SQLStatement {
 
     public static enum Type {
         TABLE, COLUMN

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

@@ -24,6 +24,7 @@ import com.alibaba.druid.sql.ast.SQLStatement;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLInsertStatement extends SQLInsertInto implements SQLStatement {
+    private String dbType;
 
     public SQLInsertStatement(){
 
@@ -85,4 +86,13 @@ public class SQLInsertStatement extends SQLInsertInto implements SQLStatement {
             visitor.endVisit(this);
         }
     }
+
+    @Override
+    public String getDbType() {
+        return dbType;
+    }
+    
+    public void setDbType(String dbType) {
+        this.dbType = dbType;
+    }
 }

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

@@ -18,9 +18,12 @@ package com.alibaba.druid.sql.ast.statement;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.alibaba.druid.sql.SQLUtils;
 import com.alibaba.druid.sql.ast.SQLHint;
+import com.alibaba.druid.sql.ast.SQLObject;
 import com.alibaba.druid.sql.ast.SQLObjectImpl;
 import com.alibaba.druid.sql.ast.SQLOrderBy;
+import com.alibaba.druid.sql.ast.SQLStatement;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLSelect extends SQLObjectImpl {
@@ -118,4 +121,16 @@ public class SQLSelect extends SQLObjectImpl {
         return true;
     }
 
+    public String toString() {
+        SQLObject parent = this.getParent();
+        if (parent instanceof SQLStatement) {
+            String dbType = ((SQLStatement) parent).getDbType();
+            
+            if (dbType != null) {
+                return SQLUtils.toSQLString(this, dbType);
+            }
+        }
+        
+        return super.toString();
+    }
 }

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

@@ -21,9 +21,9 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLSelectItem extends SQLObjectImpl {
 
-    private SQLExpr expr;
-    private String  alias;
-    private boolean connectByRoot = false;
+    protected SQLExpr expr;
+    protected String  alias;
+    protected boolean connectByRoot = false;
 
     public SQLSelectItem(){