Question

我在sql server 2008中有两个表A和B. 两列中都存在Id列表A有一个新列Result 问题是表B中ID列的所有值都与表A中的id列的值匹配，那么我应该在表A的结果列中输入一个TRUE，否则为false

提前致谢

得到答案!!如果表有1000万行，则不确定性能试过自己并得到了答案

声明临时表

声明@temp表（id int，result varchar）

插入@temp选择A1.id，来自A A1内部连接B B1的A1.result A1.id = B1.id

更新@temp set result = true

Answer 1

您必须按以下方式运行2个查询才能实现您的要求。

update A set A.result = true from tableA A, tableB B where A.Id = B.Id
update A set A.result = false from tableA A, tableB B where A.Id != B.Id

Answer 2

declare @A as Table ( Id Int, Result Bit NULL );
declare @B as Table ( Id Int );
insert into @A ( Id ) values ( 1 ), ( 2 ), ( 4 ), ( 8 );
insert into @B ( Id ) values ( 1 ), ( 2 ), ( 3 ), ( 4 );
select * from @A;
select * from @B;
update A
  set Result = case when B.Id is NULL then 0 else 1 end
  from @A as A left outer join
    @B as B on B.Id = A.Id;
select * from @A;

Answer 3

试试这个

Update tableA a 
set result = true 
where exists (select 1 from tableB b where a.id=b.id);

Update tableA a 
set result = false
where not exists (select 1 from tableB b where a.id=b.id);

如果两个不同表的列值匹配，则添加值

3 个答案: