AutoIncremented Number

public string NewRequestID()
{
string NewID = "";
SqlDataAdapter da = default(SqlDataAdapter);
DataTable dt = null;
da = new SqlDataAdapter("select top 1 code from EmpMaster order by code desc", con);
dt = new DataTable();
da.Fill(dt);
if (dt.Rows.Count != 0)
{
string str = dt.Rows[0]["Code"].ToString();
int i = Convert.ToInt32(str.Substring(1));
NewID = (i + 1).ToString();
int start = NewID.Length + 1;
//Position from where 0 has to be inserted to the RequestID.
for (int j = start; j <= (str.Length - 1); j++)
{
NewID = "0" + NewID;
}
NewID = "A" + NewID;
}
else
{
NewID = "A000001";
}
return NewID;
}