大神们，帮看下这个查询SQL语句有什么问题。

前两个参数没有问题，可是最后一个参数怎么也得不到数据。
就是

C# code

sb.Append(" and student.StudentName like '%@studentName%'");

不知有什么问题？

谢谢各位大神了！！！

C# code

public List<Result> SearchStudentResultByGradeIdAndSubjectIdAndStudentName(string gradeId, string subjectId, string studentName)        {            StringBuilder sb = new StringBuilder();            sb.Append("select result.StudentNo,result.SubjectNo,Result.studentResult,ExamDate from "                                     +"Result join subject on result.SubjectNo=Subject.SubjectNo join Student on "                                     +"Result.StudentNo=Student.StudentNo where 1=1");            if (gradeId != "-1")            {                sb.Append(" and Subject.GradeId=@gradeId");            }            if (subjectId != "-1")            {                sb.Append(" and Subject.SubjectNo=@subjectId");            }            if (studentName != "")            {                sb.Append(" and student.StudentName like '%@studentName%'");            }            SqlParameter[] para = new SqlParameter[]            {                new SqlParameter("@gradeId",gradeId),                new SqlParameter("@subjectId",subjectId),                new SqlParameter("@studentName",studentName)            };

[解决办法]
sb.Append(" and student.StudentName like '%"+@studentName+"%'");

[解决办法]

SQL code

sb.Append(" and student.StudentName like '%"+@studentName+"%'");
[解决办法]
这里  like '%@studentName%'"  不能加引号，引号会自动加上去，%你可以拼接或者写在变量里