MySQL-在MySQL UPDATE或SELECT查询中使用If If Else [英] MySQL - Using If Then Else in MySQL UPDATE or SELECT Queries

问题描述

如何在评估为True的条件下更新表并设置不同的值.

How do I update a table and set different values upon the condition evaluating to True.

例如:

UPDATE Table
SET A = '1' IF A > 0 AND A < 1
SET A = '2' IF A > 1 AND A < 2
WHERE A IS NOT NULL;

我在过程和函数中看到了CASE表达式和IF表达式，但是我想在简单的update/select语句中使用它.我可能对这个可爱的开源数据库寄予厚望吗?

I have seen CASE expression and IF expression in Procedures and Functions but I want to use it in a simple update/select statement. Is it possible or am I expecting too much from this lovely open source database?

推荐答案

UPDATE table
SET A = IF(A > 0 AND A < 1, 1, IF(A > 1 AND A < 2, 2, A))
WHERE A IS NOT NULL;

如果A始终是浮点值> 0和<= 2

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