我有多个表,表1:
ID Name
1 Adam
2 Bob
...
表2:
ID Visit
1 2019-01-01
2 2019-01-02
1 2019-01-03
1 2019-01-04
2 2019-01-04
1 2019-01-05
...
我想获得从表2的最近访问每个名称表1中,如
Name LastVisit
Adam 2019-01-05
Bob 2019-01-04
我想加入他们的行列一起使用
select tbl1.name as "Name", MAX(tbl2.visit) as LastVisit
from table1 tbl1 join table2 tbl2 on tbl1.id=tbl2.id;
但它不工作,我应该怎么办呢?
你只需要一个group by
:
select t1.name, MAX(t2.visit) as LastVisit
from table1 t1 join
table2 t2
on t1.id = t2.id
group by t1.name;