sql使用求助

Question

SELECT
    result_status,
    COUNT( CASE WHEN '110000000000' = city THEN city END ) AS '北京',
    COUNT( CASE WHEN '110000000000' = city THEN city END ) AS '天津',
    COUNT( CASE WHEN '110000000000' = city THEN city END ) AS '河北' 
FROM
    sys_patrol 
WHERE
    YEAR ( start_patrol_time ) = '2021' 
GROUP BY
    result_status

我需要统计不同地市的结果状态, city 种类很多,怎么不写死 实现查询结果

Answer 1

# 使用foreach代替写死代码，通过传参数变更要统计的城市
<foreach collection="citys" item="city">
    COUNT(CASE WHEN city = #{city.id} THEN city END ) AS city.name,
</foreach>

Answer 2

维护一张城市名称和种类的表，做关联查询