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 EXPRESSION 1 THEN STATEMENT 1; WHEN EXPRESSSION 2 THEN STATEMENT 2; ... WHEN EXPRESSION N THEN STATEMENT N; ELSE STATEMENT N+1; END CASE; 保留字CASE标识CASE语句的开始。选择器决定哪个WHEN子句应该被执行。每个WHEN子句都包含一个EXPRESSION以及与之关联的一个或者多个可执行语句。ELSE子句是可选...
–简单Case函数 CASE sex WHEN ‘1’ THEN ‘男’ WHEN ‘2’ THEN ‘女’ ELSE ‘其他’ END ...
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 case when 子结构,...
SELECT CASE WHEN age < 18 THEN 'Minor' WHEN age BETWEEN 18 AND 65 THEN 'Adult' ELSE 'Senior' END AS age_group FROM users; 在这个示例中,CASE 子句的顺序很重要,因为它决定了如何根据 age 列的值将用户分类到不同的年龄组。 参考链接 Microsoft SQL Server: CASE Statement Oracle: CASE Statemen...
is similar to an IF-THEN-ELSE statement. Oracle checks each condition starting from the first condition (left to right). When a particular condition is satisfied (WHEN part) the expression returns the tagged value (THEN part). If none of the conditions are matched, the value mentioned in ...
Oracle's Guide to Preventing NULL Values in to_date Function Question: I possess a working select statement with a where clause containing a statement similar to this... """. The start date of the camp, when converted to the format 'MM/DD/YYYY', should be greater than or e...
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 stored procedure that has a case statement. Here is the implementation. ...
oracle.javatools.db.sql Contains an API for declaratively parsing SQL queries (SELECT statements). Uses ofCaseStatement.WhenTheninoracle.javatools.db.sql Methods inoracle.javatools.db.sqlthat returnCaseStatement.WhenThen Modifier and TypeMethod and Description ...
SQL> create or replace function f_test (par_report_date in date) 2 return sys_refcursor 3 is 4 l_str varchar2(200); 5 rc sys_refcursor; 6 begin 7 l_str := 'select * from ' || 8 case when par_report_date <= trunc(sysdate) - 40 then 'history_data' 9 else 'current_data'...