private void button1_Click(object sender, EventArgs e) { if (tbUser.Text.Trim().Length == 0) { MessageBox.Show("请输入用户名!"); tbUser.Focus(); return; } if (tbPWD.Text.Trim().Length == 0) { MessageBox.Show("请输入密码!"); tbPWD.Focus(); return; } common com = new common(); database db = new database(); int t = 0; string sql = "select count(*)from manager where username='******'and password='******'"; t = db.runSqlInt(sql); if (t > 0) { this.Hide(); main fmain = new main(); fmain.User = tbUser.Text.Trim(); fmain.Show(); } else { MessageBox.Show("用户名或者密码错误!"); } }