IF语句有三种使用方式:IF、IF...ELSE...、IF...ELIF....。这三种方式根据实际的情况灵活选择。 (1)IF 语法结构: IF condition THEN statement; END IF; 1. 2. (2) IF...ELSE...结构语法结构: IF condition THEN statements ; ELSE statements; END IF; 1.
代码语言:sql 复制 IF condition BEGIN -- statements if condition is true END ELSE BEGIN -- statements if condition is false END 其中,condition是一个逻辑表达式,根据条件的真假执行相应的语句块。 在PostgreSQL中,可以使用CASE语句来实现条件判断: 代码语言:sql 复制 SELECT column1, column2, CASE WHEN co...
1. 什么是 IF ELSE 语句 IF ELSE语句允许我们根据条件的真或假来流转程序的执行路径。它的基本形式如下所示: IF<condition>THEN<statements_if_true>ELSE<statements_if_false>ENDIF; 1. 2. 3. 4. 5. 在SQL 中,条件表达式通常是布尔类型的结果,即要么为真(TRUE),要么为假(FALSE)。 2. 在 MySQL 中的 ...
It executes the ELSE statement and prints the message for it. In this case, we have two SQL IF statements. The second IF statement evaluates to false, therefore, it executes corresponding ELSE statement 它执行ELSE语句并为其打印消息。 在这种情况下,我们有两个SQL IF语句。 第二条IF语句的计算结...
PostgreSQL offers several decision-making statements such asIF,IF-THEN-ELSE,IF-THEN-ELSIF, etc. All these decision-driven statements are used to control the flow of the SQL statements based on specific criteria. In Postgres, theIFandIF-THEN-ELSEstatements evaluate only one condition; however, the...
statements END IF; IF...THEN...ELSE statements specify an alternative set of statements that should be executed if the condition evaluates to FALSE. In the following example, the previous example is modified so that an IF...THEN...ELSE statement is used to display the textNon-commissionif ...
else if (x < 0) - checks if x is less than 0 Here, both the test conditions are False. Hence, the statement inside the body of else is executed. Nested if...else Statements in R You can have nested if...else statements inside if...else blocks in R. This is called nested if....
D. Use nested IF...ELSE statementsThe following example shows how an IF...ELSE statement can be nested inside another. Set the @Number variable to 5, 50, and 500, to test each statement.SQL העתק DECLARE @Number INT; SET @Number = 50; IF @Number > 100 PRINT 'The ...
oracle 的sql里面是没有直接的if else 语句的,可以用decode函数或者case when简单的代替。比如selcect decode(表1的列1,等于a,结果a,等于b,结果b,其他结果c) from 表1。case when也可以。SELECT SEX, ( CASE SEX WHEN 'F' THEN '男' WHEN 'M' THEN '女' ELSE ' ' END ) 性别 FROM table真正的...
SQL 过程中的 IF 语句 可使用 IF 语句来根据条件满足状态而有条件进入某个逻辑。IF 语句在逻辑上等价于带有搜索式 CASE 语句 WHEN 子句的 CASE 语句。 IF 语句支持使用可选 ELSE IF 子句和缺省 ELSE 子句。END IF 子句是指示语句结尾所必需的。 以下是包含 IF 语句的过程的示例:...