MySQL case when then function use

One 、 Concept

Function description ： Judge the meaning of data display ( similar java if)
grammar ：

CASE [col_name] WHEN [value1] THEN [result1]…ELSE [default] END

Two 、 actual combat

Create and data

CREATE TABLE `user`  (
  `id` bigint(0) NOT NULL AUTO_INCREMENT COMMENT 'id',
  `account` varchar(16) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT ' account number ',
  `password` varchar(16) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT ' password ',
  `status` bit(1) NULL DEFAULT NULL COMMENT ' state ：1 normal ,0 Ban ',
  `create_date` timestamp(0) NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP(0) COMMENT ' Creation time ',
  `update_date` timestamp(0) NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP(0) COMMENT ' Update time '
)

INSERT INTO `user` VALUES (1, 'lanys', '123', b'1', '2022-06-10 11:03:34', '2022-06-10 11:03:34');
INSERT INTO `user` VALUES (2, 'Tom', '123', b'1', '2022-06-10 11:03:35', '2022-06-10 11:03:35');
INSERT INTO `user` VALUES (3, 'David', '111', b'0', '2022-06-10 11:03:38', '2022-06-10 11:03:38');

Case a

demand ： Display the account information status in the data sheet in Chinese （ state ：1 -> normal , 0-> Ban ）.
Realization effect ：

sentence ：

SELECT id,account,PASSWORD,
	( CASE STATUS WHEN 1 THEN ' normal ' WHEN 0 THEN ' Ban ' ELSE NULL END ) AS STATUS 
FROM `user`

Case 2

demand ： Set the table data according to the creation time （create_date） What sort statistics do （ Similar timeline ）.
Realization effect ：

sentence ：

SELECT create_date,
	CONCAT_WS(
	',',
	CONCAT( ' Create account account：', account ),
	CONCAT( ' password password：', PASSWORD ),
	CONCAT( ' Account status ：', CASE STATUS WHEN 1 THEN ' normal ' WHEN 0 THEN ' Ban ' ELSE NULL END ) 
	) AS line_info 
FROM `user` ORDER BY create_date