Php mySQL在哪里加入？

是否可以在mysql JOIN语句中添加WHERE，例如：

$result = mysql_query("SELECT * FROM site_products JOIN site_trans ON site_products.product_count = site_trans.trans_inventory WHERE site_products.product_id = site_trans.trans_product");

这可能吗

SELECT * FROM site_products JOIN site_trans ON (site_products.product_count = site_trans.trans_inventory AND site_products.product_id = site_trans.trans_product) WHERE 1 选择*从站点\产品加入站点\交易（站点\产品.产品\计数=站点\交易.交易\库存，站点\产品.产品\ id=站点\交易.交易\产品） 其中1

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是，这是可能的，但您的查询可能不会给出所需的结果：

SELECT * FROM site_products 
JOIN site_trans ON site_products.product_count = site_trans.trans_inventory 
WHERE site_products.product_id = site_trans.trans_product

相反，您应该将其作为附加的连接条件编写，如下所示

SELECT * FROM site_products 
JOIN site_trans ON site_trans.trans_inventory = site_products.product_count
     AND site_trans.trans_product = site_products.product_id

您还可以添加WHERE子句

SELECT * FROM site_products 
JOIN site_trans ON site_trans.trans_inventory = site_products.product_count
     AND site_trans.trans_product = site_products.product_id
WHERE site_products.product_id = 2

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是的，这可以在MYSQL连接查询中使用where条件。即使您可以使用AND运算符使用多个where条件。

连接后将执行where。如果要将where更改为

和

？@k102它将起作用，您必须使用（AND）after ON，所以查询将如下所示：

SELECT*FROM site\u products JOIN site\u trans ON（site\u products.product\u count=site\u trans.trans\u inventory AND site\u products.product\u id=site\u trans.trans\u product）

您只需执行它就可以看到它确实是可能的。@Wojtek实际上我知道它是正确的（意思是语法）-我不知道OP想要什么是否正确