C#SQLServer数据库通用访问类

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace thinger.cn.ADO.NETTeach
{
///
/// 数据库的通用类
///
public class SQLHelperBase
{
//定义连接字符串
private static string connString = “Server=.;DataBase=MISDB;Uid=sa;Pwd=123456”;

    /// <summary>/// 执行增删改操作/// </summary>/// <param name="cmdText">SQL语句</param>/// <returns></returns>public static int ExecuteNonQuery(string cmdText){//【1】创建连接对象SqlConnection conn = new SqlConnection(connString);          //【2】创建Command对象SqlCommand cmd = new SqlCommand(cmdText, conn);try{//【3】打开连接conn.Open();//【4】执行操作return cmd.ExecuteNonQuery();}catch (Exception ex){//根据需要把异常信息写到日志中...throw new Exception($"执行方法ExecuteNonQuery()发生异常：{ex.Message}");}finally{//【5】关闭连接conn.Close();}           }/// <summary>/// 执行返回单行单列的结果查询/// </summary>/// <param name="cmdText"></param>/// <returns></returns>public static object ExecuteScalar(string cmdText){          SqlConnection conn = new SqlConnection(connString);         SqlCommand cmd = new SqlCommand(cmdText, conn);try{              conn.Open();             return cmd.ExecuteScalar();}catch (Exception ex){//根据需要把异常信息写到日志中...throw new Exception($"ExecuteScalar()发生异常：{ex.Message}");}finally{             conn.Close();}}/// <summary>/// 执行返回一个多行多列结果集的查询/// </summary>/// <param name="cmdText"></param>/// <returns></returns>public static SqlDataReader ExecuteReader(string cmdText){SqlConnection conn = new SqlConnection(connString);SqlCommand cmd = new SqlCommand(cmdText, conn);try{conn.Open();return cmd.ExecuteReader(CommandBehavior.CloseConnection);}catch (Exception ex){//根据需要把异常信息写到日志中...throw new Exception($"ExecuteReader()发生异常：{ex.Message}");}//finally  //这个地方是不能关闭的//{//    conn.Close();//}}
}

}