一、查詢SQL格式：
SELECT <>
FROM <>
[LEFT、RIGHT] JOIN <>
WHERE <>
GROUP BY <>
HAVINT <>
ORDER BY<>
LIMIT <>,<>
二、“A 且 排除B”方式查詢：
A 且 非B
1、使用連接查詢
SELECT <> FROM a LEFT JOIN b ON a.id = b.id WHERE b.id IS NULL
巧妙利用連接查詢特點，將a表的在b表中無對應項的記錄查出
2、使用EXISTS關鍵字查詢
SELECT <> FROM a WHERE NOT EXISTS ( SELECT * FROM b WHERE a.id = b.id )
三、MySQL中代替“FULL JOIN”的用法：
MySQL中無“FULL JOIN”的用法，可使用UNION關鍵字拼接左右連接查詢語句并對查詢結果去重，最終實現需要的查詢
A 且 B
SELECT <> FROM a LEFT JOIN b ON a.id = b.id
UNION
SELECT <> FROM a RIGHT JOIN b ON a.id = b.id
A且B且非AB
SELECT <> FROM a LEFT JOIN b ON a.id = b.id WHERE b.id IS NULL
UNION
SELECT <> FROM a RIGHT JOIN b ON a.id = b.id WHERE a.id IS NULL
