mysql的if-else判别字段

SELECT
app.app_key as appKey,

d.account_child_balance AS 子账本余额,
d.policy AS 计费类型,
d.discount AS 正在执行折扣率,
d.discount_start_time AS 折扣开始时间,
d.discount_end_time AS 折扣结束时间,    
CASE 
    WHEN app.status = 0 THEN '创建'
    WHEN app.status = 3 THEN '已上线'
    WHEN app.status = 5 THEN '封禁'
    WHEN app.status = 8 THEN '已删除'
    WHEN app.status = 9 THEN '删除中'  
END

as app状态,
app.status ,
FROM

info_boss_account_developer AS d

LEFT JOIN info_app AS app ON app.app_id = d.app_id
WHERE

d.status = 1

AND d.service_id = 1003
AND app.app_key IN ('z3v5yqkbzi3z0','tdrvipksty7o5')
ORDER BY

FIELD(app.app_key,'z3v5yqkbzi3z0','tdrvipksty7o5')

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