問題截圖在下面了，有SQL大神指教一下吧。
uj5u.com熱心網友回復：
(1.)SELECT A.ACCOUNT,USERS=COUNT(B.TELEPHONE),RENT=SUM(A.RENT),FEE01=SUM(B.FEE01),FEE02=SUM(B.FEE02),FEE03=SUM(B.FEE03),FEE04=SUM(B.FEE04)
FROM USER A
JOIN CHARGE B
ON A.TELEPHONE=B.TELEPHONE
GROUP BY A.ACCOUNT
(2.)SELECT A.ACCOUNT
FROM USER A
JOIN CHARGE B
ON A.TELEPHONE=B.TELEPHONE
GROUP BY A.ACCOUNT
HAVING COUNT(B.TELEPHONE)>3
(3).SELECT A.TELEPHONE
FROM USER A
JOIN CHARGE B
ON A.TELEPHONE=B.TELEPHONE
WHERE (B.FEE01+B.FEE02+B.FEE03+B.FEE04)>A.RENT*1.5
uj5u.com熱心網友回復：
用explain命令看一下這條陳述句。看一下這2張表的索引。
uj5u.com熱心網友回復：
寫個查詢SQL還得分析索引了嗎，SQL都沒整出來哪來的優化
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標籤：MySQL
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