improve parser ddl support

src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerExprParser.java

@@ -129,6 +129,11 @@ public class SQLServerExprParser extends SQLExprParser {
                 accept(Token.RPAREN);
             }
             
+            if (lexer.token() == Token.PERCENT) {
+                lexer.nextToken();
+                top.setPercent(true);
+            }
+            
             return top;
         }
         

src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerLexer.java

@@ -39,6 +39,7 @@ public class SQLServerLexer extends Lexer {
         map.put("TOP", Token.TOP);
         map.put("USE", Token.USE);
         map.put("WITH", Token.WITH);
+        map.put("PERCENT", Token.PERCENT);
 
         DEFAULT_SQL_SERVER_KEYWORDS = new Keywords(map);
     }

src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerSelectParser.java

@@ -76,9 +76,7 @@ public class SQLServerSelectParser extends SQLSelectParser {
             }
 
             if (lexer.token() == Token.TOP) {
-                SQLServerTop top = new SQLServerTop();
-                lexer.nextToken();
-                top.setExpr(createExprParser().primary());
+                SQLServerTop top = this.createExprParser().parseTop();
                 queryBlock.setTop(top);
             }
 
@@ -101,7 +99,7 @@ public class SQLServerSelectParser extends SQLSelectParser {
         return queryRest(queryBlock);
     }
     
-    protected SQLExprParser createExprParser() {
+    protected SQLServerExprParser createExprParser() {
         return new SQLServerExprParser(lexer);
     }
 }

src/main/java/com/alibaba/druid/sql/dialect/sqlserver/visitor/SQLServerOutputVisitor.java

@@ -96,6 +96,10 @@ public class SQLServerOutputVisitor extends SQLASTOutputVisitor implements SQLSe
             print(")");
         }
         
+        if (x.isPercent()) {
+            print(" PERCENT");
+        }
+        
         return false;
     }