需要帮助进行样本数据输入 [英] need help for sample data entry

问题描述

每个人都美好的一天

请在编写这个简单易用的程序时需要帮助

它只有三个文本框和一个按钮即可保存它们

这是我的代码

Imports System.Data
Imports System.Data.SqlClient



Public Class Form1

    Dim cmd As SqlCommand
    Dim con As SqlConnection
   
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim ConID As String
        Dim ConAddress As String
        Dim ConPhone As String

        ConID = Me.TextBox1.Text
        ConAddress = Me.TextBox2.Text
        ConPhone = Me.TextBox3.Text
        Try


            con.ConnectionString = "Data Source=DBS;Initial Catalog=Recruitment ;User Id=myuserid;Password=Mypassword"
            con.Open()
            cmd.Connection = con
            cmd.CommandText = "INSERT INTO Contacts(ConID, ConAddress,ConPhone ) VALUES(''" & ConID & "'' , ''" & ConAddress & "'' , ''" & ConPhone & "'') "
        Catch ex As Exception
            MessageBox.Show("Error while inserting record on table..." & ex.Message, "Insert Records")
        Finally
            con.Close()
        End Try



    End Sub

End Class

解决方案

如果conID为数字，则无需将其用引号引起来.

 "  & ConID& " & ConAddress&  '，'"& ConPhone&   

建议:您应该将命令与参数或过程一起使用.

不起作用:(

它一直告诉我这个错误

在表上插入时出错...对象引用未设置为对象的实例"

这是什么意思?

首先，在您的语句中使用参数，不要将文字连接到SQL文本.有关更多信息，请参见: SqlParameter [ Dim con As 新 SqlConnection Dim cmd As 新建 SqlCommand

另一件事是，您设置了sql语句，但是根据您的代码，您根本不会执行它.使用 ExecuteNonQuery [

解决方案

If conID is numeric, you need not enclose it in quotes.

"INSERT INTO Contacts(ConID, ConAddress,ConPhone ) VALUES(" & ConID & " , '" & ConAddress & "' , '" & ConPhone & "') "

Suggestion: You should use command with parameters or procedures.

not working :(

it keeps telling me this error

" Error while inserting on table... Object Reference not set to an instance of an object "

what is that mean ?

First of all, use parameters in your statement, don''t concatenate literals to the SQL text. More info, see: SqlParameter [^]. When you use parameters, you don''t have to worry for example about data type conversions etc.

The problem looks like that you define the connection and the command variables but you don''t create instances of those classes at all. So try changing to:

Dim con As New SqlConnection
Dim cmd As New SqlCommand

Another thing is that you set the sql statement but based on your code you don''t execute it at all. Use ExecuteNonQuery[^] to actually execute the statement

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