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

子查询中select count(1) as num from A where A.ID = B.ID 就是统计B表和A表用ID连接的行数 子查询的行数=0,就可以实现从B表中排除A表数据

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)

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】

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, count(B) as total, sum(case when B > 30 then 1 else 0 end) as total1, sum(case when B > 20 then 1 else 0 end) as total2 from ABC group by A

limit 10不能在 order 后面哦

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。

你这是从一个数据表中查询还是两个数据表中查询啊,因为你给的都是tab1,还有一定要写到一起,是不是有关联,关联在哪个字段上面?你要写清楚,我才知道你想要的SQL语句了

Count排序语法如下: Select * from (Select Count(字段名) as 别名 from 表名 Group By 字段名) as [查询1] order by [查询1].字段 Count语句不支持where和order by,把他先整理成一个查询,再去排列筛选就好了。

Sql Server用函数getdate()获取当前日期时间 sql="select count(*) from [admin] where datediff(dd,logintime,getdate())=0"

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