Example Analysis of the use of case when in MySQL

This article mainly introduces the example analysis of the use of case when in MySQL, which has a certain reference value, and interested friends can refer to it. I hope you can learn a lot after reading this article.

First, let's create the database table:

CREATE TABLE `tdemo` (`id` int (32) NOT NULL, `name` varchar (255) DEFAULT NULL, `age` int (2) DEFAULT NULL, `num` int (3) DEFAULT NULL, PRIMARY KEY (`id`) ENGINE=InnoDB DEFAULT CHARSET=utf8

Insert data:

INSERT INTO `t _ demo` VALUES ('1Qing,' Zhang San', '21th,' 69')

INSERT INTO `t _ demo` VALUES ('2Qing,' Li Si', '22Qing,' 98')

INSERT INTO `t _ demo` VALUES ('3pm,' Wang Wu', '20pm,' 54')

INSERT INTO `t _ demo` VALUES ('4Qing,' Zhao Tian', '22Qing,' 80')

MySQL case when usage

SELECT *, CASE WHEN t.num > = 85 THEN 'excellent' WHEN t.num

= 60 THEN 'General' ELSE 'failed' END AS levelFROM t_demo t

Query structure:

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