数据库-使用DataReader的简单实例(两种办法)

ADO.NET包含两种类库:

1. SQLOLEDB
2. SQL

程序界面

程序清单

 

 1  Imports  System.Data
 2  Imports  System.Data.OleDb
 3  Imports  System.Data.SqlClient
 4  Public   Class  Form1
 5       Dim  strConnect  As   String   =   " Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=lzTest;Data Source=SVCTAG-4T7582X "   ' 连接字符串编写借助了udl文件
 6 
 7       Private   Sub  Button1_Click( ByVal  sender  As  System.Object,  ByVal  e  As  System.EventArgs)  Handles  Button1.Click
 8           ' 使用SQLOLEDB方式
 9           ' 连接对象是OleDBConnection对象
10           ' Command对象是OleDBCommand对象
11           ' DataReader对象是OleDBDataReader对象
12           Dim  myConnect  As   New  OleDbConnection()
13          myConnect.ConnectionString  =  strConnect
14           Try
15              myConnect.Open()  ' 打开数据库
16               Dim  myCommand  As   New  OleDbCommand( " select * from employees " , myConnect)  ' 打开表
17               Dim  myDataReader  As  OleDbDataReader
18              myDataReader  =  myCommand.ExecuteReader()
19              ListBox1.Items.Clear()
20               While  (myDataReader.Read())
21                  ListBox1.Items.Add(myDataReader.GetString( 1 ))  ' ps:姓名列是第二列,列序号从0开始,所以这里填1
22               End   While
23           Catch  ex  As  Exception
24               MsgBox (ex.ToString(), MsgBoxStyle.AbortRetryIgnore,  " 出现异常 " )
25           Finally
26               If  myConnect.State  =  ConnectionState.Open  Then
27                  myConnect.Close()
28               End   If
29           End   Try
30       End Sub
31 
32       Dim  strConn2  As   String   =   " server=SVCTAG-4T7582X;Integrated Security=SSPI;Persist Security Info=False;database=lzTest "
33 
34       Private   Sub  Button2_Click( ByVal  sender  As  System.Object,  ByVal  e  As  System.EventArgs)  Handles  Button2.Click
35           ' 使用SqlConnection类库,需要先引入System.data.SqlClient
36           ' PS: 连接字符串不需要Provider值,其他关键字也不同
37           ' 连接对象是SQLConnection对象
38           ' Command对象是SQLCommand对象
39           ' DataReader对象是SQLDataReader对象
40           Dim  myConn  As  SqlConnection  =   New  SqlConnection()
41          myConn.ConnectionString  =  strConn2
42           Try
43              myConn.Open()
44               Dim  command1  As  SqlCommand  =   New  SqlCommand( " select * from employees " , myConn)
45               Dim  DataReader1  As  SqlDataReader
46              DataReader1  =  command1.ExecuteReader()
47              ListBox1.Items.Clear()
48               While  (DataReader1.Read())
49                  ListBox1.Items.Add(DataReader1.GetValue( 1 ).ToString())
50               End   While
51           Catch  ex  As  Exception
52               MsgBox (ex.ToString())
53           Finally
54               If  myConn.State  =  ConnectionState.Open  Then
55                  myConn.Close()
56               End   If
57           End   Try
58       End Sub
59  End Class
60