MySQL左聯多表查詢where條件寫法示例
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責編：小采
時間：2020-11-09 21:01:21
MySQL左聯多表查詢where條件寫法示例
MySQL左聯多表查詢where條件寫法示例: 代碼如下: select * from _test a left join _test b on a.id=b.id where a.level='20' and a.month='04' and b.level='20' and b.month='03'; select a.*,b.* from (select * from _test where
導讀MySQL左聯多表查詢where條件寫法示例: 代碼如下: select * from _test a left join _test b on a.id=b.id where a.level='20' and a.month='04' and b.level='20' and b.month='03'; select a.*,b.* from (select * from _test where
代碼如下:
select * from _test a left join _test b on a.id=b.id where a.level='20' and a.month='04' and b.level='20' and b.month='03';
select a.*,b.* from (select * from _test where level='20' and month='04') as a left join (select * from _test where level='20' and month='03') as b on a.id=b.id;
這兩條語句結果是不同的，應該是left join的時候如果條件是多個表mysql會自動轉成內聯導致，第二條語句才能達到正確的目的(為了找到相差的兩條數據)。
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MySQL左聯多表查詢where條件寫法示例
MySQL左聯多表查詢where條件寫法示例: 代碼如下: select * from _test a left join _test b on a.id=b.id where a.level='20' and a.month='04' and b.level='20' and b.month='03'; select a.*,b.* from (select * from _test where
