MySQL COUNT加統計條件

COUNT((('字段名' = '條件') OR NULL)) 

-- 列子如下 在IP段列表顯示下面IP總數量，空閑數量，故障數量
SELECT A.*,COUNT(B.id) AS totalip,COUNT(((B.use_status = 1) OR NULL)) AS idleip,COUNT(((B.use_status = 4) OR NULL)) AS faultip 
FROM icab_ipsegment AS A
LEFT JOIN icab_ip AS B ON A.id = B.ipsegment_id
GROUP BY A.id

執行結果

 

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