相关疑难解决方法(0)

为简单起见,假设所有相关字段都是NOT NULL.

你可以做:

SELECT
    table1.this, table2.that, table2.somethingelse
FROM
    table1, table2
WHERE
    table1.foreignkey = table2.primarykey
    AND (some other conditions)

要不然:

SELECT
    table1.this, table2.that, table2.somethingelse
FROM
    table1 INNER JOIN table2
    ON table1.foreignkey = table2.primarykey
WHERE
    (some other conditions)

这两个是以同样的方式工作MySQL吗？

我想知道SQL在这些连接语句上执行的方式是否有任何不同:

SELECT * FROM a,b WHERE a.ID = b.ID

SELECT * FROM a JOIN b ON a.ID = b.ID

SELECT * FROM a JOIN b USING(ID)

有性能差异吗？还是算法差异？

或者只是语法糖？