Sql触发器不工作

Question

嗨，我有一个学生表，其中我有像用户名，usertype，密码等列 我已经写了一个触发器，为这个表创建一个用户名为usertype'学生'这里是触发代码

> 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 ; 

这是工作之前，但现在它显示出一些错误，指出，有近一个语法错误“==”学生'）声明我VARCHAR（2）。等我不知道如何解决它 请帮助您的宝贵答案。提前致谢。我试过“如果（usertype ='学生'）THEN”，但它然后显示错误消息像语法错误附近declare我varchar（2）;

Answer 1

当我浏览手册上，我看不到任何==支持，

• MySQL OPERATORS

因此，在你TRIGGER，只应IF (usertype = 'Student') THEN

FULL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 ; 

Answer 2

你确定mysql允许==作为相等运算符吗？