计数SQL查询常是excuting退出记录，但记录是不是在数据库

我不知道WOT是计数查询的问题。它总是说，reocord存在于数据库中...

但记录不是代雷。

什么是计数SQL查询的问题..

<pre>MAcmd.CommandText = "SELECT Count(*) FROM roles Select userid,groupid from users,groups WHERE username = '" + TextBox1.Text + "' AND name = '" + TextBox2.Text + "'";

            int count =(int)MAcmd.ExecuteScalar();

            if(count>0)

            {

                Label1.Text="record exits";

            }

            else

            {

            MAcmd.CommandText = "INSERT INTO ROLES (UserId,GroupId) SELECT UserId,GroupId FROM Users, Groups WHERE username= '" + TextBox1.Text + "' AND name='" + TextBox2.Text + "'";

 

            MAcmd.ExecuteNonQuery();

            //MessageBox.Show("Inserted Sucessfully");

            Label1.Text = "inserted";

            }

            MAconn.Close();