I. Introduction

1. Purpose

This article realizes that VB.Net connects to oracle to query data through OleDbConnection, and displays the data to TextBox1.

2. Database version

select * from v$version;

	BANNER
1	Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
2	PL/SQL Release 11.2.0.1.0 - Production
3	CORE 11.2.0.1.0 Production
4	TNS for 64-bit Windows: Version 11.2.0.1.0 - Production
5	NLSRTL Version 11.2.0.1.0 - Production

3.IDE version

Microsoft Visual C++ 2019

Second, the source code

1. Page design

2. Click on the event to query the database

Imports System.Data.OleDb

Public Class oracleDemo

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        '创建数据库连接
        Dim oleDbCon As New OleDbConnection
        '连接字符串192.168.31.55
        Dim conStr = "(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))
(CONNECT_DATA=(SERVICE_NAME=orcl)))"
        oleDbCon.ConnectionString = "Provider=OraOLEDB.Oracle;Data Source=" + conStr +
         ";user id=scott;password=root"
        'Command 对象提供执行 SQL命令的功能
        Dim oleDbCmd As New OleDbCommand()
        '打开连接
        oleDbCon.Open()
        '设置 Command 对象的连接属性
        oleDbCmd.Connection = oleDbCon
        '定义sql
        Dim sql = "select 'aa' from dual"
        '查询真正的数据库
        sql = "SELECT * FROM EMP --where empno = '7369'"
        oleDbCmd.CommandType = CommandType.Text
        '设置查询语句
        oleDbCmd.CommandText = sql
        'DataReader 对象提供只读方式的数据对象
        Dim dataRd As OleDbDataReader
        '查询数据
        dataRd = oleDbCmd.ExecuteReader()
        Dim a = "返回结果："

        '这样只能查询出第一条结果 
        'If dataRd.Read() Then
        '    a += CStr(dataRd.GetValue(0))
        'Else
        '    MsgBox("错误")
        'End If

        '这样能查询出全部数据
        While dataRd.Read = True
            a += CStr(dataRd.GetValue(0))
            'TextBox1.Text.Append(str)
            a += ","
        End While

        '在TextBox1中显示显示查询结果
        TextBox1.Text = a
        dataRd.Close()
        oleDbCon.Close()
    End Sub

End Class

Three, test

Four, matters needing attention

1. Exception: "OraOLEDB.Oracle" provider is not registered on the local computer

Prompt that this exception is handled as follows

Click: Project->Properties->Compile, uncheck "Prefer 32-bit (P)"

VB.NET connects to oracle through OleDbConnection to query data example