Mysql 计数 : only showing one result

Question

我想知道在 MySQL 数据库中统计数据的正确查询是什么。

比如我想统计有缺席备注的数据。所以结果应该是。

|stud_name    |total_absent|
|John Bandola |13          |
|Jeff Oliveras|10          |
|Wendy Lizardo|5           |

等等

但问题是，它只显示 1 个这样的结果

|stud_name    |total_absent|
|John Bandola |13          |

这是我的问题

SELECT 
    stud_name, 
    COUNT(remark) as total_absent 
FROM tb_attendance 
WHERE instructor_id = 'INST-20131296' 
    AND subj_code = 'C100' 
    AND description = 'ADBMS' 
    AND remark = 'Absent'

Answer 1

由于您需要每个 stud_name 的汇总结果，因此您需要根据该字段分组:

SELECT 
    stud_name, 
    COUNT(remark) as total_absent 
FROM tb_attendance 
WHERE instructor_id = 'INST-20131296' 
    AND subj_code = 'C100' 
    AND description = 'ADBMS' 
    AND remark = 'Absent'
GROUP BY `stud_name` -- here