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sql Count详细用法

Count 返回集合中项目的数量(具体数目取决于集合).语法 维度 Dimensions.Count 返回多维数据集中的维度数,其中包括 [Measures] 维度.级别 Dimension|Hierarchy.Levels.Count 返回维度或层次结构中的级别数,包括 [All] 级别(

好像看明白了 select b,(select count(*) from x where a='b'),c,(select count(*) from x where a='c'),d,(select count(*) from x where a='d'),a,count(*) from x 你是不是要这种效果??? 嗯,很浪费资源的说 最好分开取值

count是统计的函数 count是统计表中所有字段满足where里条件的行数, 这里的count (1)=count(*)应该是统计这个表中满足where里条件的行数 并把值赋给@tempID

select 字段a,count(case when (条件) then 表1.字段b end) as c from 表1 inner join 表2 on 表1.字段=表2.字段 可以用case加条件.

过多繁琐的sql影响代码质量,及维护成本,以下为两种小技巧处理方式,仅供参考.第一种,用case ---when---方法 select id,sum(case when type in (1,2) then [count] else 0 end) as sum1,sum(case when type in (3) then [count] else 0 end) as sum

select * from(SELECT vcani,count(*) as a FROM [Ssd_FeeStat].[dbo].[SSD_FeeData_0571_2012] group by vcani order by a) Awhere A.a>10

举个例子吧用slq语句实现除去字段T中重复的项:ID T1 1-22 2-33 3-44 1-25 2-3所要结果:ID T1 1-22 2-33 3-4 ===================================================select a.id,a.t from Table_1 as a inner join(select id=min(id) from Table_1 group by t) as b on a.id=b.id select * from Table_1 where ID in (select id=min(id) from Table_1 group by t)

select id, count(*) from t group by id order by id

1、全部计数:SELECT COUNT(0) FROM 2、条件计数:SELECT COUNT(0) FROM WHERE = 3、分组计数:SELECT , , COUNT(0) FROM GROUP BY ,

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