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  • Combox绑定数据/带查询功能

      private void button3_Click(object sender, EventArgs e)
            {
                string sql = "select dname,did from department";

                SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=hem09;User ID=sa;Password=123456");
                try
                {
                    SqlCommand cmd = new SqlCommand(sql, conn);
                    conn.Open();
                    SqlDataReader reader= cmd.ExecuteReader();

                    //将数据绑定到列表框中
                    cboList.Items.Clear();
                    //通过循环读取每一行的数据
                    while (reader.Read())//延迟执行
                    {
                        //使用索引器读取数据
                        //reader[1]
                        //reader["dname"]
                        //使用方法的方式读取,不需要进行类型转换
                        string dname=reader.GetString(0);//参数为列的索引
                        //注意:这里的索引,不是根据表的结构来确定的,而是根据select子句的结果集决定的
                        cboList.Items.Add(dname);

                       cboList.AutoCompleteMode = AutoCompleteMode.SuggestAppend;//查询功能
                           cboList.AutoCompleteSource = AutoCompleteSource.ListItems;//查询功能
                    }
                    reader.Close();
                    reader.Dispose();
                    cmd.Dispose();

                    //cmd.CommandText = "";
                }
                catch
                {
                    //...
                }
                finally
                {
                    conn.Close();
                    conn.Dispose();
                }
            }

      private void cbTitle_SelectedIndexChanged(object sender, EventArgs e)
            {
                textBox1.Text = cbTitle.SelectedItem.ToString();//下拉框值传入其它组件中
                
            }

            private void button4_Click(object sender, EventArgs e)
            {
                string sql = "select dname,did from department";
                using (SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=hem09;user id=sa;Password=123456"))
                {
                    SqlCommand cmd = new SqlCommand(sql, conn);
                    conn.Open();//尽量晚的打开连接,尽量早的关闭连接
                    SqlDataReader reader = cmd.ExecuteReader();

                    //将数据绑定到列表
                    cboList.Items.Clear();
                    while (reader.Read())
                    {
                        Department d1 = new Department() {Did=reader.GetInt32(1),Dname=reader.GetString(0)};
                        cboList.Items.Add(d1);
                        cboList.DisplayMember = "Dname";//指定对象的某个属性用于显示
                    }
                    reader.Close();
                    reader.Dispose();
                }
            }

            private void button5_Click(object sender, EventArgs e)
            {
                //1、构造sql语句
                string sql = "select * from department";
                //2建立连接
                using (SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=hem09;User id=sa;Password=123456"))
                {
                    //3.1构造命令对象
                    SqlCommand cmd = new SqlCommand(sql, conn);
                    //2.1打开连接
                    conn.Open();
                    //3.2执行命令
                    using (SqlDataReader reader = cmd.ExecuteReader())
                    {
                        //清空原有数据
                        gvList.Rows.Clear();
                        gvList.Columns.Clear();
                        //新建列
                        gvList.Columns.Add("did","编号");
                        gvList.Columns.Add("dname", "名称");
                        //遍历查询结果集,将数据添加到列表中
                        while (reader.Read())
                        {
                            Department d1 = new Department() { Did = reader.GetInt32(0), Dname = reader.GetString(1) };
                            gvList.Rows.Add(d1.Did, d1.Dname);
                        }
                    }
                    cmd.Dispose();
                }
            }

              
           

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  • 原文地址:https://www.cnblogs.com/haimingkaifa/p/5361440.html
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