-- 将当前数据库中, 所有表的smalldatetime 列改为nvarchar(20)

-- 如果列上有索引/默认值之类的依赖项, 则无法修改

EXEC sp_msforeachtable
    @command1 = N'
DECLARE CUR CURSOR LOCAL
FOR
SELECT
    N''ALTER TABLE ? ALTER COLUMN ''
       + QUOTENAME(C.name)
       + N''nvarchar(20)''

FROM syscolumns C, systypes T
WHERE C.xusertype = T.xusertype
    AND T.name = ''smalldatetime''
    AND C.id = OBJECT_ID(N''?'')
OPEN CUR

DECLARE @s nvarchar(4000)
FETCH CUR INTO @s

WHILE @@FETCH_STATUS = 0

BEGIN
    PRINT(@s)
    EXEC(@s)
    FETCH CUR INTO @s

END

CLOSE CUR
DEALLOCATE CUR

',
    @whereand = N'
       AND EXISTS(
              SELECT * FROM syscolumns C, systypes T
              WHERE C.xusertype = T.xusertype
                  AND T.name = ''smalldatetime''
                  AND C.id = O.id)
'