如果所有表都不存在,添加列吗? [英] Add a column if it doesn't exist to all tables?
问题描述
我正在使用SQL Server 2005/2008。我需要向表中添加一列(如果尚不存在)。这将应用于给定数据库中的所有表。我希望我能近在咫尺,但是我对这个解决方案有疑问。
I'm using SQL Server 2005/2008. I need to add a column to a table if it does not yet exist. This will apply to all tables in a given database. I hoped I was close, but I'm having issues with this solution.
这怎么办?
这就是我所拥有的:
EXEC sp_MSforeachtable '
declare @tblname varchar(255);
SET @tblname = PARSENAME("?",1);
if not exists (select column_name from INFORMATION_SCHEMA.columns
where table_name = @tblname and column_name = ''CreatedOn'')
begin
ALTER TABLE @tblname ADD CreatedOn datetime NOT NULL DEFAULT getdate();
end
'
但是我得到了错误:
错误102:'@tblname'附近的语法不正确。
CreatedOn附近的语法不正确。
@tblname附近的语法不正确。
CreatedOn附近的语法不正确。
...依此类推,对于每个表。
Error 102: Incorrect syntax near '@tblname'. Incorrect syntax near 'CreatedOn'. Incorrect syntax near '@tblname'. Incorrect syntax near 'CreatedOn'. ... and so on, for each table.
推荐答案
在DDL中使用变量,例如@tableName。此外,将名称分成部分并忽略模式只会导致错误。您应该只在SQL批处理参数中使用?替换,并依靠 MSforeachtable
替换:
You cannot use variables, like @tableName, in DDL. Besides, splinting the name into part and ignoring the schema can only result in bugs. You should just use the ''?'' replacement in the SQL batch parameter and rely on the MSforeachtable
replacement:
EXEC sp_MSforeachtable '
if not exists (select * from sys.columns
where object_id = object_id(''?'')
and name = ''CreatedOn'')
begin
ALTER TABLE ? ADD CreatedOn datetime NOT NULL DEFAULT getdate();
end';
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