一.效果圖

QQ圖片20181202153157.gif

二.描述主要功能

通過(guò)主界面選擇收銀員或者庫(kù)管員登陸绊谭，在輸入相應(yīng)的賬號(hào)密碼彈出相應(yīng)的界面

image.png

image.png

三.ADO.NET查詢數(shù)據(jù)庫(kù)的流程

1.連接字符串

2.鏈接數(shù)據(jù)庫(kù)
sqlConn.Open();

3.構(gòu)造命令
if (this.cbb_UserType.Text == "收銀員")
{
// 注意USER是SQL Server關(guān)鍵字惦蚊，表名不能命名為USER埃唯，而應(yīng)當(dāng)用USERS
sqlStr = "select * from USERS where ID=@id and PASSWORD=@pwd";
}
else
{
sqlStr = "select * from ADMIN where ID=@id and PASSWORD=@pwd";
}

4.字符串賦值
cmd.Parameters.Add(new SqlParameter("@id", this.tb_User.Text.Trim()));
cmd.Parameters.Add(new SqlParameter("@pwd", this.tb_Password.Text.Trim()));

5. 將命令發(fā)送給數(shù)據(jù)庫(kù)
   SqlDataReader dr = cmd.ExecuteReader();

四.貼入重要代碼片段青柄，并進(jìn)行詳細(xì)描述

1.將收銀員設(shè)置為默認(rèn)登錄類型

image.png

2.點(diǎn)擊登錄鍵則登錄系統(tǒng)

private void bt_Login_Click(object sender, EventArgs e)
{
String connStr = "Data Source=.;Initial Catalog=SuperMarketSales;Integrated Security=True";
SqlConnection sqlConn = new SqlConnection(connStr);
try
{
sqlConn.Open();

            String sqlStr = "";

            if (this.cbb_UserType.Text == "收銀員")
            {
                // 注意USER是SQL Server關(guān)鍵字别厘，表名不能命名為USER靖避，而應(yīng)當(dāng)用USERS
                sqlStr = "select * from USERS where ID=@id and PASSWORD=@pwd";
            }
            else
            {
                sqlStr = "select * from ADMIN where ID=@id and PASSWORD=@pwd";
            }

            SqlCommand cmd = new SqlCommand(sqlStr, sqlConn);

            // 注意是用用戶ID登錄跋理，而不是用戶名，用戶名可能會(huì)重復(fù)
            cmd.Parameters.Add(new SqlParameter("@id", this.tb_User.Text.Trim()));
            cmd.Parameters.Add(new SqlParameter("@pwd", this.tb_Password.Text.Trim()));

            SqlDataReader dr = cmd.ExecuteReader();

            // 如果從數(shù)據(jù)庫(kù)中查詢到記錄筷厘，則表示可以登錄
            if (dr.HasRows)
            {
                dr.Read();
                UserInfo.userId = int.Parse(dr["ID"].ToString());
                UserInfo.userName = dr["NAME"].ToString();
                UserInfo.userPwd = dr["PASSWORD"].ToString();
                UserInfo.userPhone = dr["PHONE"].ToString();
                UserInfo.userType = this.cbb_UserType.Text;

                MessageBox.Show(UserInfo.userType + "登錄成功");

                if (UserInfo.userType == "收銀員")
                {
                    // 顯示收銀員主界面
                    MainFormUser formUser = new MainFormUser();
                    formUser.Show();

                    // 隱藏登錄界面
                    this.Hide();
                }

                if (UserInfo.userType == "庫(kù)管員")
                {
                    // 顯示庫(kù)管員主界面
                    MainFormAdmin formAdmin = new MainFormAdmin();
                    formAdmin.Show();

                    // 隱藏登錄界面
                    this.Hide();
                }
            }
            else
            {
                MessageBox.Show("用戶名或密碼錯(cuò)誤", "提示", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
        catch (Exception exp)
        {
            MessageBox.Show("數(shù)據(jù)庫(kù)連接失敗");
        }
        finally
        {
            sqlConn.Close();
        }