drop function if exists [函数名]; delimiter [结束标记] create function [函数名]([参数1], [参数2] ...) returns [返回值类型] begin [方法体] return [返回值]; end [结束标记] delimiter ; 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 参数,其格式为param_name type,如username varchar(20)。
IF-ELSE 语法 在MySQL 中,IF-ELSE 语句的基本语法如下: IFconditionTHENstatement1;ELSEstatement2;ENDIF; 1. 2. 3. 4. 5. 其中,condition是需要判断的条件表达式,statement1和statement2分别是条件为真和条件为假时需要执行的 SQL 语句。 IF-ELSE 示例 假设我们有一个学生成绩表students,包含学生的姓名、成绩...
首先,在MySQL中创建一个存储过程: 代码语言:txt 复制 DELIMITER // CREATE PROCEDURE CheckCondition(IN input INT) BEGIN IF input > 0 THEN SELECT 'Positive'; ELSE SELECT 'Non-positive'; END IF; END // DELIMITER ; 然后,在C#中调用这个存储过程: ...
I have stored the next invoice number in a file called Storage01 in the field Nextra5. The code below deals with this and is accepted by MySQL Workbench but when I try to run it I get an error "Not allowed to return a result set from a function". But if I remove the Function, ...
对一些创建了枚举值,针对不同的枚举值有不同的操作时,枚举也可以消除if-else。个人感觉有点像策略模式或者表驱动。 优化前 enumOperateTypeEnum{ PO(1), PR(2), DC_INBOUND(3), DC_OUTBOUND(4);publicfinalInteger code; OperateTypeEnum(Integer code) {this.code = code; } }privatestaticLonggetOperator...
MySQLIFfunction is one of the MySQL control flow functions that returns a value based on a condition. TheIFfunction is sometimes referred to asIF ELSEorIF THEN ELSEfunction. The syntax of the MySQLIFfunction is as follows: 1IF(expr,if_true_expr,if_false_expr) ...
`SUPPLIER_TYPE`) IN ( '企业', '电商' ) THEN '0' WHEN tp1.`SUPPLIER_TYPE` = '个人' THEN '2' WHEN tp1.`SUPPLIER_TYPE` = '出资人' THEN '6' ELSE '4' END AS supplierType, tp1.`SUPPLIER_CLASS` AS supplierClass, GROUP_CONCAT( DISTINCT esp.`supplier_result_id` ) AS supplier...
MySQLIFfunction is one of the MySQL control flow functions that returns a value based on a condition. TheIFfunction is sometimes referred asIF ELSEorIF THEN ELSEfunction. The syntax of the MySQL IF function is as follows: IF(expr,if_true_expr,if_false_expr) ...
if if(value,value2,value3),如果value结果为true(一般为表达式),返回value2,否则value3 case when 方式1(相当Java的if..else if.. else) case when 条件1 then 结果1 when 条件2 then 结果2
There is also an IF() function, which differs from the IF statement described here. See Section 14.5, “Flow Control Functions”. The IF statement can have THEN, ELSE, and ELSEIF clauses, and it is terminated with END IF. If a given search_condition evaluates to true, the corresponding...