嗨,我有一个学生表格,其中包含用户名,用户类型,密码等列.
我已经为该表编写了一个触发器,该触发器为用户类型’Student’创建了一个用户名,这是触发器代码

> DROP TRIGGER `sasis`.`USERNAMEAutoGen`;

DELIMITER ||

CREATE TRIGGER `sasis`.`USERNAMEAutoGen` 
BEFORE INSERT ON `sasis`.`userinfo` 
FOR EACH ROW BEGIN  
    if (usertype== 'Student')
      declare i varchar(2);
      declare usrnm varchar(20);
      declare fullusrnm varchar(255);
      declare curyr varchar(10);
      declare curm varchar(10);
      declare rcount varchar(50);
      set i='I';
      select date_format(now(),'%y') into curyr;
      select date_format(now(),'%b') into curm;
      set usrnm=concat(i,curyr,upper(curm));
      select count(*) into rcount from userinfo where username like concat(usrnm,'%');
      if(rcount<9) then
        set rcount=concat('0000',(rcount+1));
      elseif (rcount<99) then
        set rcount=concat('000',(rcount+1));
      elseif (rcount<999) then
        set rcount=concat('00',(rcount+1));
      end  if;
      set fullusrnm=concat(i,curyr,upper(curm),rcount);
       if (new.username is null or trim(new.username)='') then
        set NEW.username=fullusrnm;
      end if;   end if; END||

DELIMITER ;

它以前工作过,但现在显示了一些错误,该错误表明在’==’Student’)附近声明i varchar(2)时出现语法错误.等,我不知道如何解决
请帮助您提供宝贵的答案.提前致谢.

我也尝试过“ if(usertype =’Student’)THEN”,但随后在声明i varchar(2)时显示错误消息,如语法错误；

解决方法:

当我浏览手册时,看不到任何==支持,

> MySQL OPERATORS

因此,在您的TRIGGER中,应该仅是IF(usertype =’Student’)THEN

完整的触发代码

CREATE TRIGGER `sasis`.`USERNAMEAutoGen` 
BEFORE INSERT ON `sasis`.`userinfo` 
FOR EACH ROW 
BEGIN  

    declare i varchar(2);
    declare usrnm varchar(20);
    declare fullusrnm varchar(255);
    declare curyr varchar(10);
    declare curm varchar(10);
    declare rcount varchar(50);

    IF (usertype== 'Student') THEN

        set i='I';
        select date_format(now(),'%y') into curyr;
        select date_format(now(),'%b') into curm;
        set usrnm=concat(i,curyr,upper(curm));
        select count(*) into rcount from userinfo where username like concat(usrnm,'%');

        if(rcount<9) then
            set rcount=concat('0000',(rcount+1));
        elseif (rcount<99) then
            set rcount=concat('000',(rcount+1));
        elseif (rcount<999) then
            set rcount=concat('00',(rcount+1));
        end  if;

        set fullusrnm=concat(i,curyr,upper(curm),rcount);
        if (new.username is null or trim(new.username)='') then
            set NEW.username=fullusrnm;
        end if; 

      end if; 
END||

DELIMITER ;