SQL Server表为特定数据类型占用太多空间

我个人将通过几个步骤进行此操作。您已经在此处标记了sql-server-2008和sql-server-2012，但是我假设您没有使用完全不受支持的软件：

--Add a column to replicate bad data
ALTER TABLE dbo.YourTable ADD OldID nvarchar(1200);
GO
--Put bad data in the new column
UPDATE dbo.YourTable
SET OldID = ItemID1
WHERE TRY_CONVERT(int, ItemID1) IS NULL;
GO
--Get rid of bad data in the ID column
UPDATE dbo.YourTable
SET ItemID1 = TRY_CONVERT(int, ItemID1);
GO
ALTER TABLE dbo.YourTable ALTER COLUMN ItemID1 int;
GO
--Review bad data
SELECT OldID
FROM dbo.YourTable
WHERE OldID IS NOT NULL;
GO
--Once reviewed, and action taken, drop the bad column.
ALTER TABLE dbo.YourTable DROP COLUMN OldID;