SQLHelper类

　简单的SQLHelper类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Configuration;
 7 using System.Data.SqlClient;
 8 using System.Data;
 9 
10 namespace MyDBHelper
11 {
12     public class SQLHelper
13     {
14         //获取连接字符串，从配置文件中 
15         //不加密
16         private readonly string strConn = ConfigurationManager.ConnectionStrings["strConn"].ConnectionString;
17 
18         //执行非查询语句 返回受影响的行数
19         public static int ExecuteNonQuery(string commandText,params SqlParameter[] parameters)
20         {
21             using (SqlConnection conn = new SqlConnection(strConn))
22             {
23                 using (SqlCommand cmd = new SqlCommand(commandText,conn))
24                 {
25                     cmd.CommandType = CommandType.Text;//默认是CommandType.Text
26                     if (parameters.Length > 0)
27                     {
28                         cmd.Parameters.AddRange(parameters);
29                     }
30                     conn.Open();
31                     return cmd.ExecuteNonQuery();
32                 }
33             }
34         }
35         /// <summary>
36         /// 查询符合SQL语句的数据，填充数据表中
37         /// </summary>
38         /// <param name="commandText">实质是sql语句</param>
39         /// <param name="parameters">sql语句中的参数</param>
40         /// <returns></returns>
41         public static DataTable ExecuteDataTable(string commandText,params SqlParameter[] parameters)
42         {
43             using (SqlConnection conn = new SqlConnection(strConn))
44             {
45                 conn.Open();
46                 using (SqlCommand cmd = conn.CreateCommand())//可以通过conn创建SqlCommand对象，也可以直接new
47                 {
48                     cmd.CommandText = commandText;
49                     cmd.CommandType = CommandType.Text;
50                     cmd.Parameters.AddRange(parameters);
51                     DataSet ds = new DataSet();
52                     SqlDataAdapter adapter = new SqlDataAdapter(cmd);
53                     adapter.Fill(ds);
54                     return ds.Tables[0];
55                 }
56             }
57         }
58         /// <summary>
59         /// 执行SQL语句查询 返回结果集中的第一行第一列的值
60         /// </summary>
61         /// <param name="commandText">SQL语句</param>
62         /// <param name="parameters">参数。可变参数</param>
63         /// <returns></returns>
64         public static object ExecuteScalar(string commandText,params SqlParameter[] parameters)
65         {
66             using(SqlConnection conn=new SqlConnection(strConn))
67             {
68                 conn.Open();
69                 using(SqlCommand cmd=conn.CreateCommand())
70                 {
71                     cmd.CommandText=commandText;
72                     cmd.CommandType=CommandType.Text;
73                     cmd.Parameters.AddRange(parameters);
74                     return cmd.ExecuteScalar();
75                 }
76             }
77         }
78     }
79 }