关于写sql语句解决方案

关于写sql语句
有一个主从表：
主表#t1，数据如下：
id code
1 a1
2 a2
3 a3

从表#t2(#t2.id_t1与主表#t1.id关联)，数据如下：
id id_t1 f1
1 1 t1
2 1 t2
3 3 t6


我想实现，如果#t1的数据没有对应从表#t2的数据时，就不要显示#t1的主表，
比如显示#t1主表：
id code
1 a1
3 a3

由于#t1.id=2时，找不到#t2的数据，所以不显示出来。如何写sql语句？




[解决办法]

SQL code

--> 测试数据：[t1]if object_id('[t1]') is not null drop table [t1]create table [t1]([id] int,[code] varchar(2))insert [t1]select 1,'a1' union allselect 2,'a2' union allselect 3,'a3'--> 测试数据：[t2]if object_id('[t2]') is not null drop table [t2]create table [t2]([id] int,[id_t1] int,[f1] varchar(2))insert [t2]select 1,1,'t1' union allselect 2,1,'t2' union allselect 3,3,'t6'select distinct t2.id_t1,t1.code from t2 inner join t1 on t2.id_t1=t1.idid_t1    code1    a13    a3
[解决办法]
select m.* from #t1 m where exists(select 1 from #t2 n where m.id = n.id_t1)
[解决办法]
SQL code
create table [#t1]([id] int,[code] varchar(2))insert [#t1]select 1,'a1' union allselect 2,'a2' union allselect 3,'a3'create table [#t2]([id] int,[id_t1] int,[f1] varchar(2))insert [#t2]select 1,1,'t1' union allselect 2,1,'t2' union allselect 3,3,'t6'select m.* from #t1 m where exists(select 1 from #t2 n where m.id = n.id_t1)drop table #t1 , #t2/*id          code ----------- ---- 1           a13           a3（所影响的行数为 2 行）*/