MySQL存储过程从select语句为多个变量赋值答案

【问题标题】：MySQL store procedure Assign value to multiple variable from select statementMySQL存储过程从select语句为多个变量赋值
【发布时间】：2017-03-20 12:31:46
【问题描述】：

这是我的存储过程。我有问题将值分配给声明的变量。当我执行它时，插入和更新命令工作正常，但声明变量的值保持为 0；但我在数据库中有一些价值。我怎样才能正确地做到这一点。

BEGIN
DECLARE PaidFee INT DEFAULT 0; 
DECLARE DueFee INT DEFAULT 0; 
DECLARE CourseFee INT DEFAULT 0; 
INSERT INTO `creditdirectory`(`TypeID`, `PersonName`, `CreditBy`, `PersonID`, `ModeOfPayment`,`Details`,`Amount`,`CompanyID`) 
VALUES(1,PersonName,CreditBy, AddmissionID, ModeOfPayment, 'Installment', PaidAmount, 
 CompanyID); 
SELECT `CourseFee`,`PaidFee`,`DueFee` INTO CourseFee,PaidFee,DueFee FROM `studentcoursedetails` WHERE `ID`= CourseID; 
SET PaidFee = PaidFee + PaidAmount; 
SET DueFee = CourseFee - PaidFee; 
IF (NextDueDate !='') THEN 
UPDATE `studentcoursedetails` SET `PaidFee` = PaidFee, `DueFee` = DueFee, `DueDate` = NextDueDate WHERE `ID`= CourseID; 
ELSE 
UPDATE `studentcoursedetails` SET `PaidFee` = PaidFee, `DueFee` = DueFee, `DueDate` = NULL WHERE `ID` = CourseID; 
END IF; 
END

【问题讨论】：

标签： mysql stored-procedures

【解决方案1】：

不要使用列名相同的变量，查询将优先考虑表列名。

一个好主意是使用带前缀的变量：

BEGIN
    DECLARE p_PaidFee INT DEFAULT 0; 
    DECLARE p_DueFee INT DEFAULT 0; 
    DECLARE p_CourseFee INT DEFAULT 0; 
    INSERT INTO `creditdirectory`(`TypeID`, `PersonName`, `CreditBy`, `PersonID`, `ModeOfPayment`,`Details`,`Amount`,`CompanyID`) 
    VALUES(1,PersonName,CreditBy, AddmissionID, ModeOfPayment, 'Installment', PaidAmount, 
     CompanyID); 
    SELECT `CourseFee`,`PaidFee`,`DueFee` INTO p_CourseFee,p_PaidFee,p_DueFee FROM `studentcoursedetails` WHERE `ID`= CourseID; 
    SET p_PaidFee = p_PaidFee + PaidAmount; 
    SET p_DueFee = p_CourseFee - p_PaidFee; 
    IF (NextDueDate !='') THEN 
        UPDATE `studentcoursedetails` SET `PaidFee` = p_PaidFee, `DueFee` = p_DueFee, `DueDate` = NextDueDate WHERE `ID`= CourseID; 
    ELSE 
        UPDATE `studentcoursedetails` SET `PaidFee` = p_PaidFee, `DueFee` = p_DueFee, `DueDate` = NULL WHERE `ID` = CourseID; 
    END IF; 
END

【讨论】：