在 MySQL 中强制使用索引进行连接的语法是什么
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/1272399/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
What is the syntax to force the use of an index for a join in MySQL
提问by Drarok
The use of the "FORCE/USE/IGNORE INDEX" when doing a straightforward select is well-documented, but it's not clear from the documentation how to do it for a JOIN.
在进行直接选择时使用“FORCE/USE/IGNORE INDEX”是有据可查的，但文档中不清楚如何为 JOIN 执行此操作。
How do you force a specific index to be used for a joined table?
您如何强制将特定索引用于连接表？
回答by Drarok
The FORCE/USE/IGNORE goes after the table name you are joining, and after the alias if you're using one.
FORCE/USE/IGNORE 在您加入的表名之后，如果您使用的是别名，则在别名之后。
SELECT
t1.`id` AS `id_1`,
t2.`id` AS `id_2`
FROM
`table1` t1
LEFT OUTER JOIN
`table2` t2
FORCE INDEX FOR JOIN (`table1_id`)
ON (t2.`table1_id` = t1.`id`)
