简版DBHelper类

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DBHelper类

记得引用System.Configuration

using System;using System.Collections.Generic;using System.Configuration;using System.Data;using System.Data.SqlClient;using System.Linq;using System.Text;using System.Threading.Tasks;namespace TestDAL{    public class DBHelperDAL    {        //数据库链接字符串        public static string ConnString = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;        //数据库连接对象        public static SqlConnection Conn = null;        //初始化数据库连接        public static void InitConnection()        {            //如果连接对象不存在，则创建连接            if (Conn == null)            {                Conn = new SqlConnection(ConnString);            }            //如果连接对象关闭，则打开连接            if (Conn.State == ConnectionState.Closed)            {                Conn.Open();            }            //如果连接中断，则重启连接            if (Conn.State == ConnectionState.Broken)            {                Conn.Close();                Conn.Open();            }        }        //查询，获取DataReader        public static SqlDataReader GetDataReader(string sqlStr)        {            InitConnection();            SqlCommand cmd = new SqlCommand(sqlStr, Conn);            return cmd.ExecuteReader(CommandBehavior.CloseConnection);        }        //查询，获取DataSet        public static DataSet GetDataSet(string sqlStr)        {            InitConnection();            DataSet ds = new DataSet();            SqlDataAdapter dap = new SqlDataAdapter(sqlStr, Conn);            dap.Fill(ds);            Conn.Close();            return ds;        }        //查询，获取DataTable        public static DataTable GetDataTable(string sqlStr)        {            return GetDataSet(sqlStr).Tables[0];        }        //增删改        public static bool ExecuteNonQuery(string sqlStr)        {            InitConnection();            SqlCommand cmd = new SqlCommand(sqlStr, Conn);            int result = cmd.ExecuteNonQuery();            Conn.Close();            return result > 0;        }        //执行集合函数        public static string ExectuteScalar(string sqlStr)        {            InitConnection();            SqlCommand cmd = new SqlCommand(sqlStr, Conn);            string result = cmd.ExecuteScalar().ToString();            Conn.Close();            return result;        }    }}

web.config 配置

  <connectionStrings>    <add name="DefaultConnection" providerName="System.Data.sqlClient" connectionString="server=.;database=DBTest;uid=sa;pwd=123456;"/>  </connectionStrings>

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