MySQL 连接两个不同数据库中的表？
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Join between tables in two different databases?
提问by user3262424
In MySQL, I have two different databases -- let's call them Aand B.
在 MySQL 中，我有两个不同的数据库——我们称它们为A和B。
Is it possible to perform a join between a table that is in database A, to a table that is in database B?
是否可以在数据库A中的表与数据库B 中的表之间执行连接？
回答by OMG Ponies
Yes, assuming the account has appropriate permissions you can use:
是的，假设该帐户具有适当的权限，您可以使用：
SELECT <...>
FROM A.table1 t1 JOIN B.table2 t2 ON t2.column2 = t1.column1;
You just need to prefix the table reference with the name of the database it resides in.
您只需要在表引用前面加上它所在的数据库的名称。
回答by Senthil
SELECT <...>
FROM A.tableA JOIN B.tableB
回答by Kalaivani M
SELECT *
FROM A.tableA JOIN B.tableB
or
或者
SELECT *
FROM A.tableA JOIN B.tableB
ON A.tableA.id = B.tableB.a_id;
回答by Noel Swanson
SELECT <...>
FROM A.table1 t1 JOIN B.table2 t2 ON t2.column2 = t1.column1;
Just make sure that in the SELECT line you specify which table columns you are using, either by full reference, or by alias. Any of the following will work:
只需确保在 SELECT 行中通过完整引用或别名指定您正在使用的表列。以下任何一项都将起作用：
SELECT *
SELECT t1.*,t2.column2
SELECT A.table1.column1, t2.*
etc.
