MySQL分組查詢統計

GROUP BY

1、有個店鋪表，字段為區域id，設備數量，店鋪名稱，如下：

2、如何按區域 district 統計 每個區域的設備數量，SQL如下

SELECT
    district,
    SUM( device_num ) AS device_num 
FROM
    `t_life_shop` 
GROUP BY
    ( district )

查詢結果

3、TP5.1寫法

$list = $this->field('district, SUM(device_num)as device_num')->group('district')->select();