Try something like:
public string CheckAssess(string emailAddress, string columnName)
{
string chkAssess;
string MgrAssessQry = "SELECT '"+columnName+"' FROM tblAllUsers";
MgrAssessQry += " WHERE email ='" + emailAddress + "'";
SqlCommand cmdReadAssess = new SqlCommand(MgrAssessQry, cn);
cn.Open();
SqlDataReader readAssess = cmdReadAssess.ExecuteReader();
while(readAssess.Read())
{
// Add the rows
chkAssess = readAssess["IsAssessMgr"].ToString();
}
return chkAssess;
}
I have changed your SqlDataReader instantiation to the line where you execute the query Same way like in this example from MSDN
http://msdn.microsoft.com/es-es/library/system.data.sqlclient.sqldatareader(v=vs.110).aspx