“对象引用未设置为对象的实例”错误 [英] "Object reference not set to an instance of an object" error

问题描述

我想创建连接字符串并将其用于我的应用程序中的所有表单但显示错误。



下面是我的代码，但显示错误对象引用没有设置为对象的实例



请帮忙!!!!!!!



我尝试过：

I want to create connection string and use it to all forms in my application but is showing error.

Below is my code but its showing error "Object reference not set to an instance of an object"

Please Help!!!!!!!

What I have tried:

mports System.Data.SqlClient
Imports System.Data.OleDb

Module sqlserverconnectionstring
    Public connsql As SqlConnection    
    Dim connstr As String     

    Public Sub sqlserverconnection()
        Try
             connstr = "Provider=SQLOLEDB.1; Data Source=" & My.Settings.sqlservername & ";Initial Catalog=" & My.Settings.sqlDBname & ";Password=" & My.Settings.sqlPswd & ";User ID=" & My.Settings.sqlUserName
             connsql.Open()

        Catch ex As Exception
            MsgBox(ex.Message.ToString)

        End Try
    End Sub
    Public Sub sqlserverdisconnectdatabase()
        Try
            connsql.Close()
        Catch myerror As SqlClient.SqlException

        End Try
    End Sub
End Module

推荐答案

您尚未实例化 connsql 。请参阅粗体代码：

You haven't instantiated connsql. See bolded code:

connstr = "Provider=SQLOLEDB.1; Data Source=" & My.Settings.sqlservername & ";Initial Catalog=" & My.Settings.sqlDBname & ";Password=" & My.Settings.sqlPswd & ";User ID=" & My.Settings.sqlUserName
connsql = New SqlConnection(connstr)
connsql.Open()

connstr =Data Source =& My.Settings.sqlservername& ;初始目录=& My.Settings.sqlDBname& ;密码=& My.Settings.sqlPswd& ;用户ID =& My.Settings.sqlUserName

connsql =新的SqlConnection（connstr）

connsql.Open（）

connstr = "Data Source=" & My.Settings.sqlservername & ";Initial Catalog=" & My.Settings.sqlDBname & ";Password=" & My.Settings.sqlPswd & ";User ID=" & My.Settings.sqlUserName
connsql = New SqlConnection(connstr)
connsql.Open()

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