使用mysql的可选参数的解决方法

Question

我试图从mssql转换存储过程 - ＆gt; MySQL的。并且坚持使用可选参数，因为mysql不支持它。对于mssql，参数初始化为NULL，并且基于p_Mode值调用不同的语句。是否有解决方法？ 我转换的MySQL存储过程是这样的：

    CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_tblLogin`(
    p_LoginId int/* =null */,
    p_LoginName varchar(100)/* =null */,
    p_Email varchar(100)/* =null */,
    p_Username varchar(20)/* =null */,
    p_Password varchar(20)/* =null */,
    p_Rights int/* =null */,
    p_Mode varchar(25))
    BEGIN

    IF (p_Mode='Insert') THEN 
    IF NOT EXISTS (SELECT * FROM tblLogin WHERE Username=p_Username)
    THEN
        INSERT INTO tblLogin(LoginName,Email,Username,Password,Rights,ModifiedDate) VALUES(p_LoginName,p_Email,p_Username,p_Password,p_Rights,now());
    END IF;
    END IF;

    IF (p_Mode='View') 
    THEN
        SELECT * FROM tblLogin;
    END IF;

    IF (p_Mode='ViewByID') 
    THEN
        SELECT * FROM tblLogin WHERE LoginId = p_LoginId;
    END IF;

    IF (p_Mode='ChkLogin') 
    THEN
        SELECT * FROM tblLogin WHERE Username = p_Username and Password = p_Password;
    END IF;

    IF (p_Mode='Update') 
    THEN
        UPDATE tblLogin
        SET `LoginName` = p_LoginName
          ,`Email` = p_Email
          ,`Username` = p_Username
          ,`Password` = p_Password
          ,`Rights` = p_Rights
          ,`ModifiedDate` = now()
        WHERE LoginId = p_LoginId;
    END IF;

    IF (p_Mode='Delete') 
    THEN
        DELETE FROM `tblLogin` WHERE LoginId = p_LoginId;
    END IF;

    END