MySQL错误代码：1060

Question

所以为此，我们的目标是在名为FullFeePaid的名为ENROLLMENT的表中添加一个列并填充该列（假设为null），但只有两个可能的答案可以是Yes或No来比较另一个名为Course的表中的数据。

所以我使用alter键入以下命令但是我一直收到一条重复的消息，即使我从未创建过一个名为FullFeePaid的列。

但在此之前，我一直收到一条错误消息，说它出现语法错误

"set e.FullPaid = if(c.fee - e.amount <= 0 'yes', 'no')". 


SET SQL_SAFE_UPDATES = 0;
ALTER TABLE enrollment
    add fullfeepaid varchar(45) NULL;

UPDATE ENROLLMENT as e
    JOIN COURSE as c on e.CourseNumber = c.CourseNumber
set e.FullFeePaid = if(c.fee - e.amountpaid <= 0 'yes', 'no')
where e.CourseNumber = c.CourseNumber;

select * 
from enrollment;

Answer 1

如果评估为true，则您想要返回的条件和结果之间缺少逗号：

UPDATE ENROLLMENT as e
    JOIN COURSE as c on e.CourseNumber = c.CourseNumber
SET e.FullFeePaid = if(c.fee - e.amountpaid <= 0, 'yes', 'no')
-- Missing comma in the OP ---------------------^
WHERE e.CourseNumber = c.CourseNumber;