in exists from join 子查询速度对比分析

in exists from join子查询速度对比分析

场景不同速度不同没有谁比谁快

 

场景1:查询大学学生(大一,大二,大三,大四)

student:

id ,name, classid

class:

id,name,parentid

 

 

语句一:select id,name from student where classid in (1,2,3,4);

语句二:select id,name from student where classid in (select id from class where parentid = 3

语句三:select id,name from student inner join (select id from class where parentid=3) as tmp on student.classid=tmp.id;

未经允许不得转载:开心乐窝-乐在其中 » in exists from join 子查询速度对比分析

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