www.5213.net > SQL语句理解 sElECt * From B whErE (sElECt Count...

SQL语句理解 sElECt * From B whErE (sElECt Count...

假设个例子吧:A表 id 姓名 性别 00 aa 女 01 bb 女 02 cc 女 B表 id 姓名 性别 00 aa 女 02 cc 女 03 dd 男 select * from B是执行B表, 当执行id=‘00’时 ,因为select count(1) as num from A where A.ID = B.ID 不等于0 所以运行结果没有第一...

select count(*) from aa where (select * from aa where a=1)错了 select count(*) from aa where a=1 select count(*) from aa where a in (select a from aa where a=1)

Mysql中可以执行,符合mysql规范,默认返回第一条记录的id 但是oracle不能执行,报ORA-00937,所以不符合oracle规范

sql="select count(*) from Cui where Time like '%2011%'"; 这样就可以了 楼主看下 like的用法吧

select a. col1, b.col2 from (select count(id) as col1 from table1) as a, (select count(id) as col2 from table2) as b -------------这样写。

一、简单查询语句 1. 查看表结构 SQL>DESC emp; 2. 查询所有列 SQL>SELECT * FROM emp; 3. 查询指定列 SQL>SELECT empmo, ename, mgr FROM emp; SQL>SELECT DISTINCT mgr FROM emp; 只显示结果不同的项 4. 查询指定行 SQL>SELECT * FROM emp WHE...

select countB)from A group by B order by B SQL语句就可以做了,例检索表格aaa,添加一列“re_num”,显示a列值重复的次数, 次数为表格按a列分组计算记录数: select a,count(a) as 're_num' from aaa group by a, select a1.a2.re_num from aaa ...

SELECT + COUNT(编号) + FROM + 职工表 + WHERE + YEAR(NOW())- + YEAR(进厂日期) + >=25 获取 编号的数量 来自于 职工表 条件是 当前年分-进厂日期 >= 25 【工龄>= 25 的职工数量】

select怎么写成selcet了,语句的意思是找出A中C=1的a与B中d=1的b相同 select count(*) from (select a from dbo.A where c=1 intersect select b from dbo.B where d=1) as C select distinct count(*) from (select a from dbo.A where c=1 int...

提示的意思是:在数据表中未找到regip这个字段。至于为什么,你就要自己检查了,我们不清楚你的数据库结构,无法明确回答你。

网站地图

All rights reserved Powered by www.5213.net

copyright ©right 2010-2021。
www.5213.net内容来自网络,如有侵犯请联系客服。zhit325@qq.com