在winform的DBHelper类(部分)

在winform的DBHelper类(部分)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
//导入命名空间
using System.Data;
using System.Data.SqlClient;

namespace oneWinForms
{
    class DBHelper
    {
        //定义连接字符串
        private static string connStr = "server=.;database=WinFormDB;uid=sa;pwd=111111";

         /// <summary>
        /// 查询方法   DataSet
        /// </summary>
        /// <param name="sql">查询sql语句</param>
        /// <returns>返回DataSet数据表格</returns>
        public static DataSet GetDataSet(string sql)
        {
            //创建数据库连接对象
            SqlConnection conn = new SqlConnection(connStr);
            //创建数据适配器对象
            SqlDataAdapter sda = new SqlDataAdapter(sql, conn);
            //创建空数据表格对象
            DataSet ds = new DataSet();
            sda.Fill(ds);
            return ds;
        }
        /// <summary>
        /// 执行增删改查语句
        /// </summary>
        /// <param name="sql">增删改sql语句</param>
        /// <returns>返回增删改执行结果</returns>
        public static bool ExecuteNonQuery(string sql)
        {
            SqlConnection conn = new SqlConnection(connStr);
            //打开数据库连接
            conn.Open();
            SqlCommand cmd = new SqlCommand(sql, conn);
            return cmd.ExecuteNonQuery() > 0;
        }

        /// <summary>
        /// 获取读取器 SqlDataReader
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static SqlDataReader GetDataReader(string sql)
        {
            SqlConnection conn = new SqlConnection(connStr);
            SqlCommand cmd = new SqlCommand(sql, conn);
            conn.Open();//打开数据库
            return cmd.ExecuteReader(CommandBehavior.CloseConnection);
        }

        /// <summary>
        /// 执行集合函数操作 查询首行首列，返回object
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="par"></param>
        /// <returns></returns>
        public static object ExecuteScalar(string sql)
        {
            SqlConnection conn = new SqlConnection(connStr);//创建数据库连接对象
            conn.Open();//打开数据库连接
            SqlCommand cmd = new SqlCommand(sql, conn);
            object result = cmd.ExecuteScalar();
            conn.Close();
            return result;
        }


    }
}