dataset小记

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

using System.Data.SqlClient;
using System.Configuration;

namespace 填充DataSet
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        string connStr = ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;
        DataSet ds = new DataSet();
        private void Form1_Load(object sender, EventArgs e)
        {
            BindCbo();
            string sql = "select sId,sName,sAge,sSex,sBirthday,sClassId from student";
            BindDgv(sql);
            //把选择的值绑定到显示控件上
            textBox1.DataBindings.Add("Text", dataGridView1.DataSource, "sName");
            textBox2.DataBindings.Add("Text", dataGridView1.DataSource, "sAge");
            textBox3.DataBindings.Add("Text", dataGridView1.DataSource, "sSex");
            comboBox1.DataBindings.Add("selectedValue", dataGridView1.DataSource, "sClassId");
        }
        void BindCbo()
        {
            DataTable dt=new DataTable();
            string sql = "select * from class";
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                using (SqlDataAdapter sda = new SqlDataAdapter(sql, conn))
                {
                    sda.Fill(dt);
                }
            }
            DataRow dr = dt.NewRow();
            dr["cName"] = "请选择";
            dr["cId"] = -1;
            dt.Rows.InsertAt(dr, 0);
            //设置下拉框 显示的列
            cboSClass.DisplayMember = "cName";
            //数据绑定  隐藏值列
            cboSClass.ValueMember = "cId";
            //数据绑定
            cboSClass.DataSource = dt;

            
        }
        void BindDgv(string sql)
        {
            //清空datatable中的数据
            if (ds.Tables.Count > 0)
            {
                ds.Tables[0].Rows.Clear();
            }
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                using (SqlDataAdapter sda = new SqlDataAdapter(sql, conn))
                {
                    sda.Fill(ds);
                }
            }
            //不自动添加列
            dataGridView1.AutoGenerateColumns = false;
            //绑定
            dataGridView1.DataSource = ds.Tables[0];
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            string sql = "select sId,sName,sAge,sSex,sBirthday,sClassId from student";
            
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                using (SqlDataAdapter sda = new SqlDataAdapter(sql, conn))
                {
                    SqlCommandBuilder scb = new SqlCommandBuilder(sda);
                    sda.Update(ds);
                }
            }
        }

        private void btnSearch_Click(object sender, EventArgs e)
        {
            string sql = "select * from Student where 1=1";
            if (cboSClass.SelectedValue.ToString() != "-1")
            {
                sql += " and sClassId=" + cboSClass.SelectedValue.ToString();
            }
            if (txtSName.Text.Length > 0)
            {
                sql += " and sName like '%" + txtSName.Text + "%'";
            }
            if (txtSSex.Text.Length > 0)
            {
                sql += " and sSex='" + txtSSex.Text  + "'";
            }
            BindDgv(sql);
        }
    }
}