DBHELPER.CS查、增、删、改例子

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 DevExpress.XtraEditors;

namespace DXApplication5
{
    public partial class Form1 : DevExpress.XtraEditors.XtraForm
    {
        public Form1()
        {
            InitializeComponent();
        }

        //绑定数据表
        private void simpleButton1_Click(object sender, EventArgs e)
        {
            //返回封装的表形式
            //this.gridControl1.DataSource = DBHelper.GetDataTable("select * from myuser");
            //普通表
            this.gridControl1.DataSource = DBHelper.GetDataSet("select * from myuser").Tables[0];
        }
        //清空数据表
        private void simpleButton5_Click(object sender, EventArgs e)
        {
            this.gridControl1.DataSource = null;
        }

        /// <summary>
        /// 表示每行生成的时候随绘制这一行数据的时候触发
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void gridView1_CustomDrawRowIndicator(object sender, DevExpress.XtraGrid.Views.Grid.RowIndicatorCustomDrawEventArgs e)
        {
            if (e.Info.IsRowIndicator && e.RowHandle >= 0)//在表格前面加行号
            {
                e.Info.DisplayText = (e.RowHandle + 1).ToString();
            }
        }

        /// <summary>
        /// 表示获取某行中某列的数据
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void gridView1_Click(object sender, EventArgs e)
        {
           
            //当表不为空时获取单元格数据有效
            if (this.gridControl1.DataSource != null)
            {
                //获取点击的行数
                int selectedHandle = this.gridView1.GetSelectedRows()[0];

                //得到该行中某列绑定字段的值 
                this.textEdit1.Text = this.gridView1.GetRowCellValue(selectedHandle, "username").ToString().Trim();
                this.textEdit2.Text = this.gridView1.GetRowCellValue(selectedHandle, "mygroup").ToString().Trim();
                this.textEdit3.Text = this.gridView1.GetRowCellValue(selectedHandle, "mystop").ToString().Trim();
            }
        }

        //新建一条数据
        private void simpleButton2_Click(object sender, EventArgs e)
        {
            //SQL语句:先查询数据是否已经存在相同的数据
            string SSQL = "select * from myuser where username='" + Convert.ToString(textEdit1.Text.Trim()) + "'";

            //使用ExecuteNonQuery指令SELECT查询时不会返回行数，因此查询需要使用ExecuteScalar指令

            if (DBHelper.ExecuteScalar(SSQL) == null)
            {
                string ADDSQL = "insert into myuser(username,mygroup,mystop)  values('" + Convert.ToString(textEdit1.Text.Trim()) + "','" + Convert.ToString(textEdit2.Text.Trim()) + "','" + Convert.ToString(textEdit3.Text.Trim()) + "')";
                int m = DBHelper.ExecuteNonQuery(ADDSQL);
                if (m > 0)
                {
                    //刷新数据表
                    this.gridControl1.DataSource = DBHelper.GetDataTable("select * from myuser");
                }
            }
            else
            {
                XtraMessageBox.Show("添加失败，已存在相同数据");
            }
        }

        //删除一条数据
        private void simpleButton3_Click(object sender, EventArgs e)
        {
            //SQL语句
            string SQL = "delete from myuser where username='" + Convert.ToString(textEdit1.Text.Trim()) + "'";
            int n = DBHelper.ExecuteNonQuery(SQL);
            if (n > 0)
            {
                //刷新数据表
                this.gridControl1.DataSource = DBHelper.GetDataTable("select * from myuser");
            }
            else
            {
                XtraMessageBox.Show("删除失败");
            }
        }

        //修改一条数据
        private void simpleButton4_Click(object sender, EventArgs e)
        {
            //SQL语句
            string SQL = "Update myuser set mygroup='" + textEdit2.Text.Trim() + "',mystop='" + textEdit3.Text.Trim() + "' " + " where username=" + "'" + textEdit1.Text.Trim() + "'";
            int n = DBHelper.ExecuteNonQuery(SQL);
            if (n > 0)
            {
                //刷新数据表
                this.gridControl1.DataSource = DBHelper.GetDataTable("select * from myuser");
            }
            else
            {
                XtraMessageBox.Show("修改失败");
            }
        }
    }
}