try
{
if (textBox6.Text == "")
{
MessageBox.Show("用户名不允许为空,并返回重输");
textBox6.Focus();
return;
}
con.Open();
com.Connection = con;
com.CommandText = String.Format("select count(*) from users where username='{0}'", textBox6.Text);
int a = (int)com.ExecuteScalar();
if (a != 0)
{
com.CommandText = String.Format("select username from users where username = '{0}'",textBox6.Text);
com.ExecuteScalar();
dgvRes.CurrentCell = dgvRes.Rows[r].Cells[0];
}
else
{
MessageBox.Show("输入的用户名不存在,请重新输入!");
textBox6.Focus();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
con.Close();
}