mysql带条件取count记录数

参考方法三:

统计sub_type='REFUND_FEE’ 的记录数:

方法一.select count(sub_type) from t where t.sub_type='REFUND_FEE’；

方法二.select sum(if( B.sub_type='REFUND_FEE’ ,1,0)) from t；

方法三.select count(B.sub_type=‘REFUND_FEE’ or null) from t；

解释：

当select B.sub_type=‘REFUND_FEE’ 时：

如果sub_type为REFUND_FEE则返回1，

不空且不为REFUND_FEE否则返回0，

空时返回null。

所以B.sub_type=‘REFUND_FEE’ or null 只返回sub_type=‘REFUND_FEE’ 的，其余的都返回null ,而count(列名)时是不会统计null的个数的

注：count(*)会把null的个数也统计在内

 

项目sql

    SELECT subjectName,doctorName,count(1) AS sumNum,
   count(OVERTIMES>0 or null) as overNum            //只统计OVERTIMES>0的数

from ht_personstream
WHERE 1=1
<if test="subjectId!='' and subjectId!='null'">
   and subjectId = #{subjectId}
</if>
<if test="startTime!='' and startTime!='null'">
   <![CDATA[ and date_format(ENDTIME, '%Y-%m-%d')>= #{startTime} ]]>        //mysql日期格式化
</if>
<if test="endTime!='' and endTime!='null'">
   <![CDATA[ and date_format(ENDTIME, '%Y-%m-%d')<= #{endTime} ]]>
</if>
GROUP BY  doctorId,subjectId



项目sql百分数保留两位小数

SELECT
subjectName as name,
concat(convert(((SUM(OVERTIMES)/(count(1)+SUM(OVERTIMES)))*100 ),decimal(10,2)),'%') as VALUE
FROM HT_PERSONSTREAM
where isDeleted = 0
GROUP BY subjectId,doctorId