ELSE语句是可选的,如果省略了ELSE语句,PL/SQL会隐含增加一个ELSE语句: ELSE RAISE CASE_NOT_FOUND; 注意:即使省略了ELSE语句,PL/SQL也会执行ELSE语句,程序执行时也会收到一个异常。 简单CASE语句声明语法如下: CASE selector_variable WHEN criterion1 TH EN criterion1_state
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 ...
SQL存储过程中的IF-ELSE语句允许您基于条件来选择不同的操作。在SQL Server中,IF-ELSE语句的语法如下: ``` IF condition BEGIN -- Statements to execute when the condition is TRUE END ELSE BEGIN -- Statements to execute when the condition is FALSE END ``` 这是一个基本的IF-ELSE语句结构,其中“...
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...
在下面SQL IF语句中,它计算表达式,如果条件为true,则执行IF块中提到的语句,否则将执行ELSE子句中的语句。 代码语言:javascript 代码运行次数:0 运行 AI代码解释 IF(Expression)BEGIN--If the condition isTRUEthen execute the following statement True Statements;ENDELSEBEGIN--If the condition is False then exec...
MySQL IF ELSEIF ELSE语句 如果要基于多个表达式有条件地执行语句,则使用IF ELSEIF ELSE语句如下: IFexpressionTHENstatements; ELSEIF elseif-expressionTHENelseif-statements; ...ELSEelse-statements;ENDIF; 如果表达式(expression)求值为TRUE,则IF分支中的语句(statements)将执行;如果表达式求值为FALSE,则如果elseif...
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 ...
Use the IF statement within PL/SQL contexts to execute SQL statements on the basis of certain criteria. The four forms of the IF statement are: IF...THEN...END IF IF...THEN...ELSE...END IF IF...THEN...ELSE IF...END IF
D. Use nested IF...ELSE statements The following example shows how anIF...ELSEstatement can be nested inside another. Set the@Numbervariable to5,50, and500, to test each statement. SQL DECLARE@NumberINT;SET@Number=50; IF @Number > 100 PRINT 'The number is large.'; ELSEBEGINIF@Number...
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....