C#开发学习——SqlHelper的使用

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
    </startup>
  <connectionStrings>
    <add name="conStr" connectionString="Data Source=.;Initial Catalog=;User ID=;Password="/>
  </connectionStrings>
</configuration>

  1 using System.Configuration;
  2 using System.Data;//DatSet..Table SqlDataAdapter
  3 using System.Data.SqlClient;//SqlConnection Command DataReader
  4 namespace Common
  5 {
  6     public class SqlHelper
  7     {
  8         //连接字符串
  9         //1、添加引用 2、导入命名空间 为了使用ConfigurationManager
 10         private static string conStr = ConfigurationManager.ConnectionStrings["conStr"].ConnectionString;
 11 
 12        //增删改查
 13         //查找数据  ExecuteScalar()返回首行首列   ExecuteReader()  DataTable
 14 
 15 
 16         /// <summary>
 17         /// 返回DataTable
 18         /// </summary>
 19         /// <param name="sql">所用的sql语句</param>
 20         /// <param name="param">可变，可以传参也可以不传参数</param>
 21         /// <returns></returns>
 22         public static DataTable ExecuteDataTable(string sql, params SqlParameter[] param)
 23         {
 24             DataTable dt = new DataTable();
 25             using (SqlConnection con = new SqlConnection(conStr))
 26             {
 27                 using (SqlDataAdapter adapter = new SqlDataAdapter(sql, con))
 28                 { 
 29                     //添加参数
 30                     adapter.SelectCommand.Parameters.AddRange(param);
 31                     //1.打开链接，如果连接没有打开，则它给你打开；如果打开，就算了
 32                     //2.去执行sql语句，读取数据库
 33                     //3.sqlDataReader,把读取到的数据填充到内存表中
 34                     adapter.Fill(dt);
 35                 }
 36             }
 37             return dt;
 38         }
 39 
 40         /// <summary>
 41         /// 执行查询，返回首行首列
 42         /// </summary>
 43         /// <param name="sql"></param>
 44         /// <param name="param"></param>
 45         /// <returns></returns>
 46         public static object ExecuteScalar(string sql, params SqlParameter[] param)
 47         {
 48             object o = null;
 49             using (SqlConnection con = new SqlConnection(conStr))
 50             {
 51                 using (SqlCommand cmd = new SqlCommand(sql, con))
 52                 {
 53                     cmd.Parameters.AddRange(param);
 54                     con.Open();
 55 
 56                     o = cmd.ExecuteScalar();
 57                 }
 58             }
 59             return o;
 60         }
 61 
 62 
 63         /// <summary>
 64         /// 执行查询，返回SqlDataReader对象
 65         /// </summary>
 66         /// <param name="sql"></param>
 67         /// <param name="param"></param>
 68         /// <returns></returns>
 69         public static SqlDataReader ExecuteReader(string sql, params SqlParameter[] param)
 70         {
 71             SqlDataReader reader = null;
 72             using (SqlConnection con = new SqlConnection(conStr))
 73             {
 74                 using (SqlCommand cmd = new SqlCommand(sql, con))
 75                 {
 76                     cmd.Parameters.AddRange(param);
 77                     con.Open();
 78 
 79                     reader = cmd.ExecuteReader();
 80                 }
 81             }
 82             return reader;
 83         }
 84 
 85         /// <summary>
 86         /// 执行增删改，返回受影响的行数
 87         /// </summary>
 88         /// <param name="sql"></param>
 89         /// <param name="param"></param>
 90         /// <returns></returns>
 91         public static int ExecuteNonQuery(string sql, params SqlParameter[] param)
 92         {
 93             int n = -1;
 94             using (SqlConnection con = new SqlConnection(conStr))
 95             {
 96                 using (SqlCommand cmd = new SqlCommand(sql, con))
 97                 {
 98                     cmd.Parameters.AddRange(param);
 99                     con.Open();
100                     n = cmd.ExecuteNonQuery();
101                 }
102             }
103             return n;
104         }
105 
106     }
107 }