private void btnLogin_Click(object sender, EventArgs e) { //判断是否输入用户名 if (tbUser.Text.Trim().Length == 0) { MessageBox.Show("请输入用户名!"); tbUser.Focus(); return; } //判断是否已输入密码 if (tbPwd.Text.Trim().Length == 0) { MessageBox.Show("请输入密码!"); tbPwd.Focus(); return; } //创建common对象 common com = new common(); //创建database对象 database db = new database(); //统计所输入的用户名和密码在对应数据表中的个数的查询语句 int t = 0; string sql = "seclect count(*) from manager wherer username='******'and pwd='" + com.md5(tbPwd.Text.Trim()) + "'"; //将对应表中数据条数放在变量t中 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!!"); } }