自学.net（1）手写一个sqlhelper类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Configuration;
 6 using System.Data.SqlClient;
 7 using System.Data;
 8 
 9 namespace SH
10 {
11     class SqlHelper
12     {
13         private static string connStr = ConfigurationManager.ConnectionStrings["dbConnStr"]
　　　　　　　　.ConnectionString;
14 
15        
16         public static int ExecuteNonQuery(string sql,params SqlParameter[] parameters)
17         {
18             using (SqlConnection conn = new SqlConnection(connStr))
19             {
20                 conn.Open();
21                 using (SqlCommand cmd = conn.CreateCommand())
22                 {
23                     cmd.CommandText = sql;
24                     //foreach (SqlParameter param in parameters)
25                     //{
26                     //    cmd.Parameters.Add(param);
27                     //}
28                     cmd.Parameters.AddRange(parameters);
29                     return cmd.ExecuteNonQuery();
30                 }
31             }
32         }
33 
34         public static object ExecuteScalar(string sql, params SqlParameter[] parameters)
35         {
36             using (SqlConnection conn = new SqlConnection(connStr))
37             {
38                 conn.Open();
39                 using (SqlCommand cmd = conn.CreateCommand())
40                 {
41                     cmd.CommandText = sql;
42                     cmd.Parameters.AddRange(parameters);
43                     return cmd.ExecuteScalar();
44                 }
45             }
46         }
47 
48         //只用来执行查询结果比较少的sql
49         public static DataTable ExecuteDataTable(string sql, params SqlParameter[] parameters)
50         {
51             using (SqlConnection conn = new SqlConnection(connStr))
52             {
53                 conn.Open();
54                 using (SqlCommand cmd = conn.CreateCommand())
55                 {
56                     cmd.CommandText = sql;
57                     cmd.Parameters.AddRange(parameters);
58 
59                     SqlDataAdapter adapter = new SqlDataAdapter(cmd);
60                     DataSet dataset = new DataSet();
61                     adapter.Fill(dataset);
62                     return dataset.Tables[0];
63                 }
64             }
65         }
66     }
67 }