when then else end 查询统计

SELECT
    COUNT(*) ,
    SUM(CASE WHEN a.order_type = ‘巡检类‘ THEN 1 ELSE 0 END) AS TYPEA,
    SUM(CASE WHEN a.order_type = ‘维修类‘ THEN 1 ELSE 0 END) AS TYPEB,
    SUM(CASE WHEN a.order_type = ‘综合类‘ THEN 1 ELSE 0 END) AS TYPEC
    FROM CMS_WORK_ORDER a
        inner JOIN au_office o3 ON o3.id = a.office_id
    where a.office_id = ‘010212‘

when then else end 查询统计

原文：https://www.cnblogs.com/carinen616/p/10278260.html