How mysql optimizes join

This article shows you how mysql optimizes join. The content is concise and easy to understand. It will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

Mysql has quite a type of column in the join table and indexes it.

If your application has a lot of JOIN queries, you should make sure that the Join fields in both tables are indexed. In this way, MySQL will start the mechanism to optimize the SQL statement of Join for you.

Moreover, these fields used for Join should be of the same type. For example, if you want to Join the DECIMAL field with an INT field, MySQL will not be able to use their indexes. For those STRING types, you also need to have the same character set. (the character sets of the two tables may not be the same)

The mechanism of the SQL statement of Arial;mso-bidi-font-family:Arial;color:#555555' >.

Moreover, these fields used for Join should be of the same type. For example, if you want to Join the DECIMAL field with an INT field, MySQL will not be able to use their indexes. For those STRING types, you also need to have the same character set. (the character sets of the two tables may not be the same)

The above is how mysql optimizes join. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.