百分率的sql

说明：
这条sql是在一张表里面进行查询，将不同的级别的工程师的百分率查询出来

第一个sql
select
   tmp.job_grade, tmp.tcount/tmp1.t1count
 from 
 (
select job_grade,count(*) tcount from cscp_exam_apply GROUP BY job_grade ) tmp
join 
(select job_grade,count(*) t1count from cscp_exam_apply where result='P' GROUP BY job_grade) tmp1
on tmp.job_grade=tmp1.job_grade




第二个sql


select
   tmp.ContentTypeID, tmp.tcount/tmp1.t1count
 from 
 (
select ContentTypeID,count(*) tcount from zccontent WHERe CatalogID=18666 GROUP BY ContentTypeID ) tmp
join 
(select ContentTypeID,count(*) t1count from zccontent where CatalogID=18668 GROUP BY ContentTypeID) tmp1
on tmp.ContentTypeID=tmp1.ContentTypeID

执行的结果：

这条sql语句的注意事项：

说明：
这个是不需要进行分组的百分率sql.

select (select count(*) from zccontent where CatalogID=18666  )/(select count(*) from zccontent where CatalogID=18668 ) Acount

执行的结果为

#这个是说明每种值的数量
select greate,COUNT(*) from class GROUP BY greate

#这个sql是说明每种值的概率
select greate,COUNT(*)/11 from class GROUP BY greate #这里的11是该表的总行数