ON 决定如何 "连接" 表， WHERE 决定连接后 "显示" 哪些行。 这个根本区别导致了在 LEFT JOIN / RIGHT JOIN 外连接中，条件放置位置会产生巨大影响；而在 INNER JOIN 中，效果通常 等价 。

SQL JOINs make it easy to find and fix missing data Your email has been sent Many people are confused by various JOIN operations supported by SQL. Learn to master the SQL command line with this crash ...

MySQL users now have another choice for support besides Oracle, which acquired the open-source database through its purchase of Sun Microsystems. SkySQL plans to offer “enterprise class support & ...