最后的成品sql如下:(需求背景是 当sender_id等于传进来的userId时,更新send_status为2;当receiver_id等于userId时,更新receiver_status为2) UPDATEmessageSETsend_status=(CASEWHENsender_id=#{userId, jdbcType=BIGINT}THEN2ELSEsend_statusEND), receive_status=(CASEWHENreceiver_id=#{userId, jdbcType=BIGINT}...
CASE语句是一种条件表达式,它允许根据不同的条件执行不同的操作。在TSQL中,可以使用CASE语句来更新多个列的值,具体步骤如下: 使用UPDATE语句来指定要更新的表和列。 在SET子句中,使用CASE语句来指定每个列的更新规则。 在CASE语句中,使用WHEN子句来定义不同的条件和对应的操作。
在SQL中,CASE WHEN语句是一种条件表达式,它允许你根据不同的条件返回不同的值。当涉及到相加值时,你可以使用CASE WHEN语句来对满足特定条件的行进行求和。以下是一个基础概念的解释以及相关示例。 基础概念 CASE WHEN语句的基本语法如下: 代码语言:txt 复制 SELECT CASE WHEN condition1 THEN result1 WHEN condition...
以下是具有含簡式 case-statement-when-clause 之 CASE 陳述式的 SQL 程序範例: CREATE PROCEDURE UPDATE_DEPT (IN p_workdept) LANGUAGE SQL BEGIN DECLARE v_workdept CHAR(3); SET v_workdept = p_workdept; CASE v_workdept WHEN 'A00' THEN UPDATE department SET deptname = 'D1'; WHEN 'B01'...
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
WHEN 1 THEN'Salaried Employee'WHEN 0 THEN'Contractor'ELSE'N/A'END FROM [HumanResources].[Employee] The downside of the simple CASE statement is that you can only check for equality. The IIF function With SQL Server 2012, theIIF functionwas introduced into the T-SQL language. The syntax is...
WHEN Salary >=50000 AND Salary <80000 THEN 'Senior Consultant' Else 'Director' END We have following output of this query. In this output, we get minimum and maximum salary for a particular designation. Update statement with a CASE statement We can use a Case statement in SQL with update...
Use CASE WHEN statement in SELECT /* mysql> SELECT Name, RatingID AS Rating, -> CASE RatingID -> WHEN 'R' THEN 'Under 17 requires an adult.' -> WHEN 'X' THEN 'No one 17 and under.' -> WHEN 'NR' THEN 'Use discretion when renting.' -> ELSE 'OK to rent to minors.' -> ...
CASE can be used in any statement or clause that allows a valid expression. For example, you can use CASE in statements such as SELECT, UPDATE, DELETE and SET, and in clauses such as select_list, IN, WHERE, ORDER BY, and HAVING. ...
--⽐如说,下⾯这段SQL,你永远⽆法得到“第⼆类”这个结果 复制代码 代码如下: CASE WHEN col_1 IN ( 'a', 'b') THEN '第⼀类' SQL语句中case,when,then的用法 SQL语句中 case, when, then的⽤法 ⽤法如下bai: 复制代码 SELECT s.s_id, s.s_name, s.s_sex, CASE WHENs.s_sex...