1、数据表

2、三层登录(未做加密处理)

• 2.1.1 UI

        BLL.LoginTblBLL loginBLL = new BLL.LoginTblBLL();

        private void btnLogin_Click(object sender, EventArgs e)
        {
            string loginName = txtLoginName.Text.Trim();
            string loginPwd = txtLoginPwd.Text;
            if (string.IsNullOrEmpty(loginName)||string.IsNullOrEmpty(loginPwd))
            {
                return;
            }
            if (loginBLL.IsLogin(loginName, loginPwd))
            {
                //登录成功
                this.DialogResult = DialogResult.OK;
            }
            else
            {
                MessageBox.Show("用户名或密码错误！");
            }

        }

• 2.1.2配置：

  <connectionStrings>
    <add name="SQLite" connectionString="Data Source=db\CaterSystem.db;version=3;"/>
  connectionStrings>

• 2.2 BLL

    public class LoginTblBLL
    {
        DAL.LoginTblDAL loginDAL = new DAL.LoginTblDAL();

        public bool IsLogin(string loginName, string loginPwd)
        {
            return loginDAL.IsLogin(loginName, loginPwd)>0;
        }
    }

• 2.3 DAL

    public class LoginTblDAL
    {
        public int IsLogin(string loginName, string loginPwd)
        {
            string sql = "select count(*) from LoginTbl where loginUid=@uid and loginPwd=@pwd";
            SQLiteParameter[] ps = {
                new SQLiteParameter("@uid",loginName),
                new SQLiteParameter("@pwd",loginPwd)
            };
            object count = SQLiteHelper.ExecuteScalar(sql, ps);
            return (int)(long)count;
        }
    }
}