SQL返回值。。。

Question

string strSql = "select count(*) from rsm_frame where roomid='a1'";
我想获得执行这条SQL语句的返回值，请问应该用什么函数？

Answer 1

SqlCommand com=new SqlCommand("select count(*) from rsm_frame where roomid='a1'",con);
con.open()
int count=(int)com.ExecuteScalar();
con.close();

Answer 2

SqlCommand com=new SqlCommand("select count(*) from rsm_frame where roomid='a1'",con);
con.open()
object var=com.ExecuteScalar();
if(var!=null)
{
   int count=(int)com.ExecuteScalar();
}con.close();

Answer 3

    SqlConnection conns = WayDataBase.getConn();
                conns.Open();                string whbc = dataGridView1.Rows[i].Cells["仓库代号"].Value.ToString();
                string sqls = "select  minus_stk from tf_ij a left join my_wh b on b.wh=a.wh where a.wh='" + whbc + "' and b.dep='" + txtDept.Text + "'";
                SqlCommand comms = new SqlCommand(sqls, conns);
                string strwh = comms.ExecuteScalar().ToString();
                if (strwh == "F")
                {
                    MessageBox.Show("库存不足，禁止保存");
                    return;
                }
                comms.Dispose();
                conns.Close();求解，我的取值不对