-- Licensed to the Apache Software Foundation (ASF) under one or more
-- contributor license agreements.  See the NOTICE file distributed with
-- this work for additional information regarding copyright ownership.
-- The ASF licenses this file to You under the Apache License, Version 2.0
-- (the "License"); you may not use this file except in compliance with
-- the License.  You may obtain a copy of the License at
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.

IF EXISTS(select * from INFORMATION_SCHEMA.columns where table_name = 'x_user' and column_name = 'user_name')
BEGIN
	IF NOT EXISTS(select * from INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE where table_name='x_user' and column_name='user_name' and constraint_name = 'x_user$x_user_UK_user_name')
    BEGIN
	    IF NOT EXISTS(select * from INFORMATION_SCHEMA.TABLE_CONSTRAINTS where table_name='x_user' and constraint_name = 'x_user$x_user_UK_user_name' and CONSTRAINT_TYPE='UNIQUE')
	    BEGIN
	        ALTER TABLE [dbo].[x_user] ALTER COLUMN [user_name] [varchar](767) NOT NULL;
	        ALTER TABLE [dbo].[x_user] ADD CONSTRAINT [x_user$x_user_UK_user_name] UNIQUE ([user_name]);
	    END
    END
END
GO
exit