can't save to database

Question

i have a 2 tables in a database..... i'm retrieving record from one table,  the insert the record into another table after changing some of the contents..... here is my code

 

void CreateRecord()

{

try

{

con.Open();

String sql = "SELECT STUD_ID, FNAME,LNAME,UNIQUE_REF,CLASSRM_ID from STUDENTS where CLASSRM_ID= '" + CLASSROOM_ID + "'";

SqlCommand cmd = new SqlCommand(sql, con);

SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);

while (rdr.Read() )

{

STUD_ID = (int)rdr[0] ;

STUD_NAME =( rdr[1] + " " + rdr[2]).ToString();

UNIQUE_REF = rdr[3].ToString();

CLASSRM_ID = (int)rdr[4];

getSelectedSubjectID();

//this is the part that does the saving and its working fine 

SaveAssessmentTemp();

}

}

finally

{

con.Close();

}

}//end  CreateRecord

 

my problem is that ..... the last record in the (first table) which was retrieved into the datareader (rdr) is been saved twice..... how do i handle this?