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MySQL,用一個(gè)查詢更新多個(gè)表

MySQL,用一個(gè)查詢更新多個(gè)表

牛魔王的故事 2019-07-02 17:21:05
MySQL,用一個(gè)查詢更新多個(gè)表我有一個(gè)更新三個(gè)表的函數(shù),但是我使用三個(gè)查詢來(lái)執(zhí)行這個(gè)操作。我希望使用一種更方便的方法來(lái)進(jìn)行良好做法。如何用一個(gè)查詢更新MySQL中的多個(gè)表?
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3 回答

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鴻蒙傳說(shuō)

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UPDATE t1

INNER JOIN t2 ON t2.t1_id = t1.id

INNER JOIN t3 ON t2.t3_id = t3.id

SET t1.a = 'something',

    t2.b = 42,

    t3.c = t2.c

WHERE t1.a = 'blah';

要查看要更新的內(nèi)容,可以將其轉(zhuǎn)換為SELECT語(yǔ)句,例如:


SELECT t2.t1_id, t2.t3_id, t1.a, t2.b, t2.c AS t2_c, t3.c AS t3_c

FROM t1

INNER JOIN t2 ON t2.t1_id = t1.id

INNER JOIN t3 ON t2.t3_id = t3.id

WHERE t1.a = 'blah';

使用與其他答案相同的表的示例:


SELECT Books.BookID, Orders.OrderID,

    Orders.Quantity AS CurrentQuantity,

    Orders.Quantity + 2 AS NewQuantity,

    Books.InStock AS CurrentStock,

    Books.InStock - 2 AS NewStock

FROM Books

INNER JOIN Orders ON Books.BookID = Orders.BookID

WHERE Orders.OrderID = 1002;


UPDATE Books

INNER JOIN Orders ON Books.BookID = Orders.BookID

SET Orders.Quantity = Orders.Quantity + 2,

    Books.InStock = Books.InStock - 2

WHERE Orders.OrderID = 1002;


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