UPDATE users SET age = 30 WHERE name = 'John Doe' AND id = 123; 如果更新操作执行缓慢,可以为name列创建索引。 代码语言:txt 复制 CREATE INDEX idx_name ON users(name); 参考链接 MySQL UPDATE Statement MySQL Indexing 通过以上信息,你应该能够理解MySQL中UPDATE语句的基础概念、优势、类型、应用场景以...
Description: When using a subquery with a case when in the update statement, the updated data does not match the expected results returned by the subquery. How to repeat: 1、prepare data: drop database if exists select_test; create database if not exists select_test; create table if not ...
Re: UPDATE statement with CASE and POSITION Jessica Jones August 24, 2011 12:33PM Re: UPDATE statement with CASE and POSITION Barry Galbraith August 24, 2011 08:04PM Sorry, you can't reply to this topic. It has been closed. Content reproduced on this site is the property of the respect...
这道题目要求我们将sex字段的m和f交换,所以可以使用case语句进行条件判断并赋给新的值。 # Write your MySQL query statement below update salary set sex = ( case sex when "m" then "f" else "m" end ); 1. 2. 3. 4. 5. 6. 7. 1.2 Leetcode 626 (Medium) 换座位 这道题目要求我们换相邻...
SELECT id, name, CASE gender WHEN 'M' THEN 'Male' WHEN 'F' THEN 'Female' ELSE 'Unknown' END AS gender_text FROM users; 参考链接: MySQL CASE Statement 请注意,以上信息仅供参考,实际应用中可能需要根据具体情况进行调整。 页面内容是否对你有帮助?
Summary: in this tutorial, you will learn how to use MySQL CASE statements to construct complex conditional statements inside stored programs. Besides the IF statement, MySQL provides an alternative conditional statement called the CASEstatement. The CASE statement makes the code more readable and ...
http://stackoverflow.com/questions/4830191/t-sql-using-a-case-in-an-update-statement-to-update-certain-columns-depending-o 这里记录一下方法,其实就是更新了你所有的可能要更新的值,在更新值的时候判断这个字段是否 要更新,不更新则附上原值,更新则附上新值。[笑哭][笑哭][笑哭][笑哭][笑哭] ...
In this case, the statement fails and rolls back. Instead, update a single table and rely on the ON UPDATE capabilities that InnoDB provides to cause the other tables to be modified accordingly. See Section 15.1.20.5, “FOREIGN KEY Constraints”. ...
语句级(STATEMENT)触发器:是指当某触发事件发生时,该触发器只执行一次; 行级(ROW)触发器:是指当某触发事件发生时,对受到该操作影响的每一行数据,触发器都单独执行一次。 语法:略 说明: BEFORE和AFTER指出触发器的触发时间分别为前触发和后触发方式,
CASE n_str WHEN n_str = 'profileStatus' THEN UPDATE tbl_contact SET status = 'A' WHERE id = id; -- The above statement updates the entire table instead of the right row WHEN n_str = 'phoneNumberMobile' THEN UPDATE tbl_contact SET mobile_phone = v_str ...