Mysql 如何在不进行两次SQL调用的情况下计算SQL中某一列中特定值的出现次数

我有一张桌子：法官（JName char（25），LawSchool char（25））

我试图在一次SQL调用中检索哈佛大学的评委人数和耶鲁大学的评委人数。我知道我能做到

SQL调用（1）

SQL调用（2）

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但是，有没有一种方法可以检索耶鲁大学和哈佛大学在oneSQL调用中的评委人数，但将它们存储在两个变量中，如cnt和cnt2？

您可以在和分组中使用

select LawSchool, count(*) as cnt 
 from Judges 
 where LawSchool in ('Harvard','Yale')
 Group By LawSchool

select LawSchool, count(*) as cnt 
from Judges where LawSchool in ( 'Harvard', 'Yale')
group by LawSchool

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您可以使用

group by

子句按唯一值分隔聚合结果：

SELECT   LawSchool, COUNT(*)
FROM     Judges
WHERE    LawSchool IN ('Harvard', 'Yale')
GROUP BY LawSchool

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伟大的谢谢你，约翰@Yusha很乐意提供帮助。您的语法在SQL Server中无效，因此我删除了标记。谢谢，很抱歉@GordonLinoff

select LawSchool, count(*) as cnt 
from Judges where LawSchool in ( 'Harvard', 'Yale')
group by LawSchool

SELECT   LawSchool, COUNT(*)
FROM     Judges
WHERE    LawSchool IN ('Harvard', 'Yale')
GROUP BY LawSchool