ADO.Net connection in C#

Question

 Hi Friends,

 

After making the ADO.Net connection, when i am trying to fetch the s_name value based on the input from textbox using below query. I am getting object reference null error. Can anybody identify what actually is the flaw in the below code

 

string @searchValue = txtStudentName.Text;

 

string sql = "SELECT * FROM Student_Detail where s_name=@searchValue"; 

 

No record is coming in sql object.

 

  SqlCommand cmd = new SqlCommand(sql, connection);