mysql - 重复条目 Mysql 主数据库

Question

此代码中出现一些错误， 尝试过调试但找不到答案。

有人可以纠正我吗？

BEGIN

DECLARE FINALID VARCHAR(8);
DECLARE MAXIDCOMPANY VARCHAR(8);

        SELECT MAX(SUBSTRING(company.idCompany,3,8))+1 INTO MAXIDCOMPANY 
        FROM company 
        WHERE SUBSTRING(company.idCompany,1,2) = SUBSTRING(nmCompany,1,2);


                IF MAXIDCOMPANY > 0 AND MAXIDCOMPANY < 10 THEN
                    SET FINALID = CONCAT(SUBSTRING(nmCompany,1,2),'00', CONVERT(MAXIDCOMPANY USING latin1));
                    ELSEIF MAXIDCOMPANY > 9 AND MAXIDCOMPANY < 100 THEN
                        SET FINALID = CONCAT(SUBSTRING(nmCompany,1,2),'0', CONVERT(MAXIDCOMPANY USING latin1));
                            ELSEIF MAXIDCOMPANY > 99  THEN
                            SET FINALID = CONCAT(SUBSTRING(nmCompany,1,2), CONVERT(MAXIDCOMPANY USING latin1));
                END IF;

                        IF MAXIDCOMPANY IS NULL THEN
                            SET FINALID = CONCAT(SUBSTRING(nmCompany,1,2),'001');
                        END IF;

                INSERT INTO company
                (company.idCompany, company.nmCompany, company.country, company.address, company.region, company.joinDate, company.quota, company.createdUser, company.createdDate, company.updatedUser, company.updatedDate)
                VALUES
                (FINALID, nmCompany, country, address, region, joinDate, quota, createdUser, NOW(), updatedUser, updatedDate);



END

这就是代码，程序在接近 1000 后停留在计数器上。

示例:

当我添加数据(例如 IN1000)作为 idCompany 时，它总是停留在该数字上，但是当我查询最大数据时，它只显示 IN999，为什么不显示 IN1000

非常感谢

Answer 1

因为max函数与SUB-STRING结合会返回变量字符内的最大值，解决办法是用count函数代替，逻辑计数会返回最大值。

SELECT COUNT(company.idCompany) + 1 INTO MAXIDCOMPANY from company where SUBSTRING(company.idCompany,1,2) = SUBSTRING(company.idCompany,1,2);

根据我的商业散文，谢谢大家的回答..