如何在 SQL Server 上执行 SQL 脚本期间显示某些内容？

例如。我有一个数据库升级脚本，用于向数据库表添加列。它看起来有点像这样：

IF NOT Exists(SELECT * FROM SysColumns sc, SysObjects so 
              WHERE sc.Name = 'dealer_number'  
              AND so.Name = 'collector'
              AND so.Type= 'U'
              AND so.id = sc.id)
BEGIN
 -- SQL for creating column
END
ELSE
BEGIN
 -- notify user that column already exists
END

如何通知用户该列已存在？

RAISERROR ('column already exists',0,1)  with nowait

or

print 'column already exists'