MySql数据库通过Select语句返回调…

DELIMITER //

DROP PROCEDURE IF EXISTS updateMachine //

CREATE PROCEDURE updateMachine

( IN inID VARCHAR(32), IN inName VARCHAR(32), IN inModeVARCHAR(32), IN inEPIDType TINYINT

, IN inISOCenter FLOAT, IN inSSD FLOAT, IN inScale TINYINT, INinWidth FLOAT, IN inHeight FLOAT, IN inIsBuild TINYINT)

BEGIN

DECLARE FLAG INT;

SET FLAG = 0;

IF inMode != '' THEN

IF !EXISTS(SELECT ID FROM Evivo.Machine WHERE ID = inMode)THEN

SELECT -1, 'MachineMode doesn\'t exists';

SET FLAG = -1;

END IF;

END IF;

UPDATE Evivo.Machine SET  Name = inName, Mode= inMode, EPIDType = inEPIDType, ISOCenter = inISOCenter

, SSD = inSSD, Scale = inScale, Width = inWidth, Height =inHeight, IsBuild = inIsBuild WHERE ID = inID;

END //

DELIMITER  ;

在Qt中用QSqlQuery类中的方法.next()指向Select返回结果，然后根据下标即可读取数据库当前记录。所以当在C++中嵌套了Sql语句时，应该使用Select语句向调用函数返回常值记录确认SQL是否达到预期结果而不是单纯语法执行通过。