MySQL分组查询统计

GROUP BY

1、有个店铺表，字段为区域id，设备数量，店铺名称，如下：

2、如何按区域 district 统计 每个区域的设备数量，SQL如下

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

查询结果

3、TP5.1写法

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