using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;
1 public class DBHelper
2 {
3 static string connStr = "Workstation id = localhost;" +
4 "Integrated Security = SSPI;" +
5 "Database = 数据库名字;";//填入SQL数据库的登录信息。
6
7
8 static SqlConnection conn = new SqlConnection(connStr);
9
10 public static SqlDataReader GetDataReader(string sql)//返回值是一个数组，可通过dr[0],dr[1]使用各字段的值
11 {
12 SqlConnection myConn = conn;
13 SqlDataReader dr = null;
14
15 try
16 {
17 if (myConn.State == ConnectionState.Closed)
18 {
19 myConn.Open();
20 }
21 SqlCommand cmd = new SqlCommand(sql, myConn);
22
23 dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
24 }
25 catch
26 {
27
28 if (myConn.State == ConnectionState.Open)
29 {
30 myConn.Close();
31 }
32
33 }
34 return dr;
35 }
36
37 public static bool ExecuteNonQuery(string sql) //对于 UPDATE、INSERT 和 DELETE 语句，返回值为该命令所影响的行数。对于所有其他类型的语句，返回值为 -1。如果发生回滚，返回值也为 -1
38 {
39 int n = 0;
40
41 try
42 {
43 if (conn.State == ConnectionState.Closed)
44 {
45 conn.Open();
46 }
47 SqlCommand cmd = new SqlCommand(sql, conn);
48 n = cmd.ExecuteNonQuery();
49
50 }
51 catch
52 {
53
54 return false;
55 }
56 finally
57 {
58 if (conn.State == ConnectionState.Open)
59 {
60 conn.Close();
61 }
62 }
63 return n > 0;
64 }
65
66 public static Object ExecuteScalar(string sql)//使用ExecuteScalar()，增删改查如果成功，会返回一个对象，否则会返回一个null；
67 {
68 Object ob = null;
69
70 try
71 {
72 if (conn.State == ConnectionState.Closed)
73 {
74 conn.Open();
75 }
76 SqlCommand cmd = new SqlCommand(sql, conn);
77 ob = cmd.ExecuteScalar();
78 }
79 catch
80 {
81 return null;
82 }
83 finally
84 {
85 if (conn.State == ConnectionState.Open)
86 {
87 conn.Close();
88 }
89 }
90 return ob;
91 }
92 }
93 }
