LEFT OUTER JOIN在MySql语法中表示为LEFT JOIN？

Question

Is LEFT OUTER JOIN expressed as just LEFT JOIN in MySQL syntax? Or are LEFT OUTER JOIN and LEFT JOIN different things in MySQL?

Answer 1

Basically they are the same.

LEFT and RIGHT are outer type join. The keyword OUTER is optional, and what this means in this case is that whether you specify it or not makes no difference.

Additional Information,

At the top level there are mainly 3 types of joins:

• INNER
• OUTER ( LEFT , RIGHT )
• CROSS