Question

[SQL]update语句中where条件数值能否用一个常量或变量代替呢？

语句如下：update 表1 set fname = (select fname from 表2 where fitem = '4' and fnumber = '123') where fnumber = '123'

经常会使用这类语句，数值123是每次都不一样的，有什么方法能替代123？只输入一次啊？现在必须输入2个123

Answer 1

DECLARE @number varchar(80)
SET @number= '123'
update 表1 set fname = (select fname from 表2 where fitem = '4' and fnumber =@number) where fnumber = @number

Answer 2

update 表1 set fname=b.fname
from 表1 a,表2 b
where a.fnumber=b.fnumber
and b.fitem='4'
and fnumber='123'

Answer 3

试试以下语句
with mtbl as ( select '123' as mycode from dual)
update 表1 set fname = (select fname from 表2 where fitem = '4' and fnumber in (select mycode from mtbl)) where fnumber in (select mycode from mtbl)