添加列前先检查

修改数据表添加列时先检查列是否存在

IF not exists(SELECT * FROM INFORMATION_SCHEMA.COLUMNS where table_name = 'System_ReportTool_Columns' and column_name = 'sRTC_Like' )
BEGIN
ALTER TABLE System_ReportTool_Columns 
ADD sRTC_Like VARCHAR(50);
print'sRTC_Like added.'
END
else 
PRINT 'sRTC_Like exists.'