add sql parser testcases

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

@@ -20,7 +20,6 @@ import java.util.List;
 
 import com.alibaba.druid.sql.ast.SQLName;
 import com.alibaba.druid.sql.ast.SQLObjectImpl;
-import com.alibaba.druid.sql.parser.Token;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLAlterTableAddIndex extends SQLObjectImpl implements SQLAlterTableItem {
@@ -35,7 +34,7 @@ public class SQLAlterTableAddIndex extends SQLObjectImpl implements SQLAlterTabl
 
     private String                           using;
     
-    private String                           keyOrIndex = Token.INDEX.name;
+    private boolean                          key = false;
 
     @Override
     protected void accept0(SQLASTVisitor visitor) {
@@ -89,11 +88,11 @@ public class SQLAlterTableAddIndex extends SQLObjectImpl implements SQLAlterTabl
         this.using = using;
     }
 
-    public String getKeyOrIndex() {
-        return keyOrIndex;
+    public boolean isKey() {
+        return key;
     }
 
-    public void setKeyOrIndex(String keyOrIndex) {
-        this.keyOrIndex = keyOrIndex;
+    public void setKey(boolean key) {
+        this.key = key;
     }
 }

src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java

@@ -1986,18 +1986,16 @@ public class SQLStatementParser extends SQLParser {
             item.setUnique(true);
             lexer.nextToken();
             if (lexer.token() == Token.INDEX) {
-                item.setKeyOrIndex(Token.INDEX.name);
                 lexer.nextToken();
             } else if (lexer.token() == Token.KEY) {
-                item.setKeyOrIndex(Token.KEY.name);
+                item.setKey(true);
                 lexer.nextToken();
             }
         } else {
             if (lexer.token() == Token.INDEX) {
-                item.setKeyOrIndex(Token.INDEX.name);
                 accept(Token.INDEX);
             } else if (lexer.token() == Token.KEY) {
-                item.setKeyOrIndex(Token.KEY.name);
+                item.setKey(true);
                 accept(Token.KEY);
             }
         }

src/main/java/com/alibaba/druid/sql/visitor/SQLASTOutputVisitor.java

@@ -2152,9 +2152,12 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Printab
             print0(ucase ? "UNIQUE " : "unique ");
         }
 
-        print0(x.getKeyOrIndex());
-        print(' ');
-
+        if (x.isKey()) {
+            print0(ucase ? "KEY " : "key ");    
+        } else {
+            print0(ucase ? "INDEX " : "index ");
+        }
+        
         if (x.getName() != null) {
             x.getName().accept(this);
             print(' ');