Why is the CASE Statement Important? The CASE WHEN statement is a valuable tool in SQL queries, offering several key benefits: Data transformation: enables you to create new columns based on the values of existing columns. Conditional aggregation: allows you to create aggregated values (e.g., ...
CASE表达式是用来判断条件的,条件成立时返回某个值,条件不成立时返回另一个值。 语法: CASEWHENComparsionConditionTHENresultWHENComparsionConditionTHENresultELSEotherEND (注:各分支返回的数据类型需一致。) (注:when子句一定要有排他性,因为当when子句为真时,剩余的when子句会被忽略。) CASE表达式的用途: 1,转换...
SQL 条件语句 (IF, CASE WHEN, IFNULL) 1、IF 1.1 表达式: IF( expr1 , expr2 , expr3 ) expr1条件,条件为true,则值是expr2 ,false,值就是expr3 示例; SELECT o.id,u.account,catagory
CASE WHEN 和COUNT CASE WHEN 和SUM CASE WHEN 和 AVG函数 与AVG函数结合,可实现计算百分比的功能 部分例子参考来自:https://www.sqlshack.com/case-statement-in-sql 你的点赞是我持续更新的动力~ 谢谢 Thanks♪(・ω・)ノ SQL学习笔记 友情链接: Y:SQL学习笔记 - 窗口函数OVER19 赞同 · 0 评论...
How do you USE CASE statement in MySQL? What is the use of CASE operator in MySQL? What is the case-switch statement in SQL? How to use a case-when statement in a mysql stored procedure? Question: To automatically set the session_id with the request_time parameter, I chose to use a...
MySQL中的case when 中对于NULL值判断的坑! sql中的case when 有点类似于Java中的switch语句,比较灵活,但是在Mysql中对于Null的处理有点特殊 Mysql中case when语法: 语法1: 1 2 3 4 5 CASE case_value WHEN when_value THEN statement_list ...
We can add as manyWHEN ... THENconditions as required in theCASEstatement. For example, -- multiple CASE conditions in SQLSELECTcustomer_id, first_name,CASEWHENcountry ='USA'THEN'United States of America'WHENcountry ='UK'THEN'United Kingdom'ENDAScountry_nameFROMCustomers; ...
CASE WHEN是 MySQL 中的条件表达式,用于在查询结果中根据条件返回不同的值。它类似于编程语言中的if-else语句,可以在 SQL 查询中实现复杂的逻辑判断。 语法 代码语言:txt 复制 CASE WHEN condition1 THEN result1 [WHEN condition2 THEN result2] ... [ELSE result] END ...
–简单Case函数 CASE sex WHEN ‘1’ THEN ‘男’ WHEN ‘2’ THEN ‘女’ ELSE ‘其他’ END ...
sql case when 用法 case when 语句是 SQL 的一个条件分支结构,它的功能是:在满 足特定条件时, 执行某特定操作。它的语法结构如下: CASE WHEN expression THEN statement [ELSE statement] END 首先,在 case when 结构中,必须要置入一个判断表达式,这个 表达式可以是比较、运算或者逻辑表达式,也可以是一个嵌套的...