Question

sql select max语法问题

sqlString="select max(CourseNo) as CourseNo from (select*from kechengxinxi where Teacher_ID='"+ID+"')";
这样写有问题么
运行时报错说‘）’附近有语法错误

Answer 1

sqlString="select max(CourseNo) as CourseNo from (select*from kechengxinxi where Teacher_ID='"+ID+"') as a "
子查询一定要给它一个名字，就是 "as a" 这种写法

追问

加 as a是什么意思

追答

不客气

Answer 2

是不是应该把某个控件里的值传给Teacher_ID，例如：where Teacher_ID='"+txtID.text+"')";

Answer 3

select max(A.CourseNo) as CourseNo from (select * from kechengxinxi where Teacher_ID='ID') A