ADO.NET连接数据库DBHelper工具类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 using System.Configuration;
 8 using System.Data;
 9 using System.Data.SqlClient;
10 
11 namespace BookStoreDAL
12 {
13     public class DBHelper
14     {
15         private static string connstr = ConfigurationManager.ConnectionStrings["mssqlserver"].ConnectionString;
16 
17         //初始化Command对象  和 Connection对象
18         public static SqlCommand PrepareCommand(string sql,CommandType cmdType,params SqlParameter[] parameters)
19         {
20             SqlCommand cmd = new SqlCommand();
21             cmd.CommandText = sql;
22             cmd.CommandType = cmdType;
23             cmd.Connection = new SqlConnection(connstr);
24             if (parameters != null)
25             {
26                 cmd.Parameters.AddRange(parameters);
27             }
28             cmd.Connection.Open();
29             return cmd;
30         }
31         //通用 增、删、改 方法
32         public static int ExecuteNonQuery(string sql,CommandType cmdType,params SqlParameter[] parameters)
33         {
34             SqlCommand cmd=PrepareCommand(sql,cmdType,parameters);
35             int count = cmd.ExecuteNonQuery();
36             cmd.Connection.Close();
37             return count;
38         }
39 
40         //查询返回单个值
41         public static object ExecuteScalar(string sql, CommandType cmdType, params SqlParameter[] parameters)
42         {
43             SqlCommand cmd = PrepareCommand(sql, cmdType, parameters);
44             object obj = cmd.ExecuteScalar();
45             cmd.Connection.Close();
46             return obj;
47         }
48 
49         //查询返回多个值的方法
50         public static SqlDataReader ExecuteReader(string sql, CommandType cmdType, params SqlParameter[] parameters)
51         {
52             SqlCommand cmd = PrepareCommand(sql, cmdType, parameters);
53             SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
54             return reader;
55         }
56     }
57 }