Winfrom窗体DBHelper执行返回datatable数据

首先创建一个DBhelper帮助类

 public class DBHelper
    {
        /// <summary>
        /// 这个属性直接可以取到app.config中配置的连接字符串
        /// </summary>
        private readonly static string config = ConfigurationManager.ConnectionStrings["aa"].ConnectionString;
        /// <summary>
        /// 离线查询，返回DataTable
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="par"></param>
        /// <returns></returns>
        public DataTable ExecuteTable(string sql, params SqlParameter[] par)
        {
            using (SqlDataAdapter sda = new SqlDataAdapter(sql,config))
            {
                if (par != null && par.Length > 0)
                {
                    sda.SelectCommand.Parameters.AddRange(par);
                }
                DataTable dt = new DataTable();
                sda.Fill(dt);
                return dt;
            }
        }
     
    }

编辑App.Config的连接字符串

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <connectionStrings>
    <add name="aa" connectionString="xxxxx"/>
  </connectionStrings>
</configuration>

winform调用

        private void button2_Click(object sender, EventArgs e)
        {

            try
            {
                DBHelper dBHelper = new DBHelper();
                string sql = string.Format(@"   SELECT FROM  TestDB sr 
where sr.status!='-1'  and sr.isdeleted = 0  and sr.planbegintime >@planbegintimel and sr.planbegintime<@planbegintimen  order by sr.planbegintime");
                SqlParameter[] parameters = {
                 new SqlParameter("@planbegintimel",DateTime.Now.ToString("yyyy-MM-dd")),
                new SqlParameter("@planbegintimen",DateTime.Now),
                };
                var table = dBHelper.ExecuteTable(sql, parameters);
                this.dataGridView1.DataSource = table;
                MessageBox.Show("查询成功");
            }
            catch (Exception ex)
            {
                MessageBox.Show("查询失败");
                log_text.Text += DateTime.Now + "查询失败：" + ex.Message + System.Environment.NewLine;
            }
        }