【WPF学习笔记】之如何设置下拉框读取SqlServer数据库的值：动画系列之（一）

先前条件：设置好数据库，需要三个文件CommandInfo.cs、DbHelperSQL.cs、myHelper.cs，需要修改命名空间，参照之前随笔http://www.cnblogs.com/Owen-ET/p/5999654.html

添加一个表的类User_test对应数据库的表，如下图：

User_test类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
using System.Data;


namespace User.sqlHelper
{
    [Serializable]
    class User_test
    {
        public User_test()
        {

        }

        #region
        private int _userID;
        private string _userName;
        private int _userGrade;
        private string _userPassword;

        public int UserID
        {
            set { _userID = value; }
            get { return _userID;  }
        }

        public string UserName
        {
            set { _userName = value;}
            get { return _userName; }
        }

        public int UserGrade
        {
            set { _userGrade = value; }
            get { return _userGrade;  }
        }

        public string UserPassword
        {
            set { _userPassword = value;}
            get { return _userPassword; }
        }

        #endregion

        #region

        public User_test(int userID)
        {
            StringBuilder strSql = new StringBuilder();
            strSql.Append("select UserID,UserName,UserGrade");
            strSql.Append(" FROM [User] ");
            strSql.Append(" where UserID=@userID");

            SqlParameter[] parameter = { 
                    new SqlParameter("@userID",SqlDbType.Int,4)};
            parameter[0].Value = userID;

            DataSet ds = DbHelperSQL.Query(strSql.ToString(), parameter);
            if( ds.Tables[0].Rows.Count > 0)
            {
                if (ds.Tables[0].Rows[0]["UserID"] != null) { this.UserID = int.Parse(ds.Tables[0].Rows[0]["UserID"].ToString().Trim()); }
                if (ds.Tables[0].Rows[0]["UserName"] != null) { this.UserName = ds.Tables[0].Rows[0]["UserName"].ToString().Trim(); }
                if (ds.Tables[0].Rows[0]["UserGrade"] != null) { this.UserGrade = int.Parse(ds.Tables[0].Rows[0]["UserGrade"].ToString().Trim()); }
                if (ds.Tables[0].Rows[0]["UserPassword"] != null) { this.UserPassword = ds.Tables[0].Rows[0]["UserPassword"].ToString().Trim(); }
            }
        }

        //根据id得到名字
        public string getUserName(int userid)
        {
            string name = "";
            StringBuilder strSql = new StringBuilder();
            strSql.Append("select UserName ");
            strSql.Append(" FROM [User] ");
            strSql.Append("where UserID=@userID");
            SqlParameter[] parameter = { 
                    new SqlParameter("@userID",SqlDbType.Int,4)};
            parameter[0].Value = userid;
            DataSet ds = DbHelperSQL.Query(strSql.ToString(), parameter);

            if(ds.Tables[0].Rows.Count > 0)
            {
                if (ds.Tables[0].Rows[0]["UserName"] != null) { name = ds.Tables[0].Rows[0]["UserName"].ToString().Trim(); }
            }
            return name;
        }

        //根据名字得到级别
        public int getUserGrade(string username)
        {
            int grade = 1;
            StringBuilder strSql = new StringBuilder();
            strSql.Append("select UserGrade ");
            strSql.Append(" FROM [User] ");
            strSql.Append(" where UserName=@userName");
            SqlParameter[] parameter = { 
                    new SqlParameter("@userName", SqlDbType.VarChar,50)};
            parameter[0].Value = username;
            DataSet ds = DbHelperSQL.Query(strSql.ToString(), parameter);

            if(ds.Tables[0].Rows.Count > 0)
            {
                if (ds.Tables[0].Rows[0]["UserGrade"] != null) { grade = int.Parse(ds.Tables[0].Rows[0]["UserGrade"].ToString().Trim()); }
            }
            return grade;
        }

        /// <summary>
        /// 增加一条数据
        /// </summary>
        /// 
        public int Add(string username)
        {
            StringBuilder strSql = new StringBuilder();
            strSql.Append("insert into [User] (");
            strSql.Append("UserName)");
            strSql.Append(" values(");
            strSql.Append("@userName)");
            SqlParameter[] parameter = { 
                    new SqlParameter("@userName",SqlDbType.VarChar,50)};
            parameter[0].Value = username;

            object obj = DbHelperSQL.Query(strSql.ToString(), parameter);
            if (obj == null)
            {
                return 0;
            }
            else 
            {
                return Convert.ToInt32(obj);
            }
        }

        /// <summary>
        /// 删除一条数据
        /// </summary>
        public bool Delete(int userid)
        {
            StringBuilder strSql = new StringBuilder();
            strSql.Append("delete from [User] ");
            strSql.Append(" where UserID=" + UserID.ToString());

            int rows = DbHelperSQL.ExecuteSql(strSql.ToString());
            if (rows > 0)
            {
                return true;
            }
            else
            {
                return false;
            }
        }


        /// <summary>
        /// 获得数据列表
        /// </summary>
        /// 
        public DataSet GetList()
        {
            StringBuilder strSql = new StringBuilder();
            strSql.Append("select * ");
            strSql.Append("FROM [User]");
            return DbHelperSQL.Query(strSql.ToString());
        }

        #endregion
    }
}

对应数据库：

然后在xaml中设置下拉框：

<UserControl x:Class="User.uc_login"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             Loaded="UserControl_Loaded"
             d:DesignHeight="1080" d:DesignWidth="1920">
    <Canvas x:Name="c_login" Width="1920" Height="1080" Background="Azure">
        <Canvas x:Name="c_log" Width="600" Height="600" Canvas.Left="680" Canvas.Top="100" Background="AntiqueWhite">
            <Label Content="用户：" Width="122" Height="80" FontSize="35" Canvas.Left="100" Canvas.Top="105" HorizontalContentAlignment="Center" VerticalContentAlignment="Center"/>
            <ComboBox x:Name="cb_uploader" Width="200" Height="80" Canvas.Left="268" Canvas.Top="105" HorizontalContentAlignment="Center" VerticalContentAlignment="Center" FontSize="35"/>
            <Label Content="密码：" Width="122" Height="80" FontSize="35" Canvas.Left="100" Canvas.Top="230" HorizontalContentAlignment="Center" VerticalContentAlignment="Center"/>
            <TextBox x:Name="tb_password" Width="200" Height="80" Canvas.Left="268" Canvas.Top="230" HorizontalContentAlignment="Center" VerticalContentAlignment="Center" FontSize="35"/>
            <Button Content="登录" Width="120" Height="60" FontSize="32" Canvas.Left="100" Canvas.Top="360" HorizontalContentAlignment="Center" VerticalContentAlignment="Center" Click="btn_login_Click"/>
            <!--<Button Content="修改密码" Width="165" Height="60" FontSize="32" Canvas.Left="305" Canvas.Top="460" HorizontalContentAlignment="Center" VerticalContentAlignment="Center" />-->
        </Canvas>
    </Canvas>
</UserControl>

注：上面代码xaml是用户控件代码。

最后，在后台代码设置：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using User.sqlHelper;
using System.Data;

namespace User
{
    /// <summary>
    /// uc_login.xaml 的交互逻辑
    /// </summary>
    public partial class uc_login : UserControl
    {
        public uc_login()
        {
            InitializeComponent();
        }

        private void UserControl_Loaded(object sender, RoutedEventArgs e)
        {
            //获取下拉框用户名字
            User_test _u = new User_test();
            DataSet _ds = _u.GetList();
            if(_ds != null)
            {
                DataTable _dt = _ds.Tables[0];
                for (int i = 0; i < _dt.Rows.Count; i++)
                {
                    string UserName = _dt.Rows[i]["UserName"].ToString().Trim();
                    ComboBoxItem cbitem = new ComboBoxItem();
                    cb_uploader.Items.Add(cbitem);
                    cbitem.Content = UserName;
                }
            }
        }

        //登录按钮
        private void btn_login_Click(object sender, RoutedEventArgs e)
        {
            //判断下拉框不为空
            if (this.cb_uploader != null)
            {
                //判断密码不为空
                if (this.tb_password != null)
                {
                    string uploader = cb_uploader.Items.
                }
                //密码为空
                else
                { 
                    
                }
            }
            //下拉框为空
            else
            { 
                
            }
        }
    }
}

结果：