tb表如下 id class sl 1 a 5 2 b 7 3 b 9 * 4 a 7 5 c 9 6 a 2 * 7
1个回答
select * from tb t1 where not exists
(select * from tb where class=t1.class and id>t1.id)
相关问题
tb表如下 id class 1 a 2 b 3 b * 4 a 5 c 6 a * 7 c * 如何以class分组,
已知集合A={1,2,3,4} B={3,4,5,6,7} C={6,7,8,9} 求(1)A∩B A∩B∩C (2)A
用perl 编程,数据如下 :12 a 4 5 6 7 13 a 8 5 7 914 a 4 2 9 615 b 7 9
若a+2b-3c=4,5a-6b+7c=8,则9a+2b-5c=______.
若a+2b-3c=4,5a-6b+7c=8,则9a+2b-5c=______.
若a+2b-3c=4,5a-6b+7c=8,则9a+2b-5c=______.
1, 4, 7, 2, 8, 3, ( ), 9 A、6 B、5 C、2 D、1
2,6,1,2,7,8,5,() A.6 B.7 C.8 D.9
1.1,1,2,2,3,4,3,5,()A.7 B.6 C.5 D.42.1,8,9,4,(),1/6A.3 B.2 C
1.1,1,2,2,3,4,3,5,()A.7 B.6 C.5 D.42.1,8,9,4,(),1/6A.3 B.2 C