mysql中join後on、where的區別

SELECT * FROM A;sql SELECT * FROM B; 以上是兩張表的機構3d   SELECT * FROM A LEFT JOIN B ON A.id=b.a_id ; 語句一 ： SELECT * FROM A LEFT JOIN B ON A.id=b.a_id AND A.id <3; 語句二： SELECT * FROM A LEFT JOIN B ON A

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