Example Analysis of execution problems between max and where in mysql

This article mainly introduces the example analysis of the execution problems between max and where in mysql. The article is very detailed and has certain reference value. Interested friends must read it!

Implementation problems between mysql max and where

Perform sql:

CREATE TABLE `grades` (`id` int (20) NOT NULL AUTO_INCREMENT, `grades` int (20) NOT NULL, `grat` varchar (20) COLLATE utf8_bin DEFAULT NULL, `grades` varchar (20) COLLATE utf8_bin DEFAULT NULL, PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8 COLLATE=utf8_bin;insert into `grades` (`id`, `gradesid`, `grat`, `grades`) values (1par 1pl 'Chinese', '80'), (2LQ' math', '89'), (3Jing' 2Zhi 'Chinese', '90') CREATE TABLE `student` (`id` int (20) NOT NULL AUTO_INCREMENT, `name` varchar (20) COLLATE utf8_bin DEFAULT NULL, PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8 COLLATE=utf8_bin;insert into `student` (`id`, `name`) values

Execution result:

Implementation result 1:

Implementation result 2:

Implementation result 3:

Implementation result 4:

Implementation result 5:

Thus it can be seen that:

1.max is executed before the where condition

two。 And group by was executed before max.

3. When where and group by appear at the same time, the where condition is executed first.

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