帮我在删除时执行操作 [英] Help me to do action at delete

问题描述

当我试图删除成功的消息显示时，请帮助我，但实际上它不会执行删除操作



我尝试了什么：



受保护的子btndelete_Click（发件人作为对象，e作为EventArgs）处理btndelete.Click



Con = New SqlConnection（数据源= VU-IT-INTERN1;初始目录=燃料系统;用户ID = sa;密码= 123）



尝试

Con.Open（）

Cmd.Connection = Con

Cmd =新的SqlCommand

Cmd.CommandText =DELETE FROM燃料，其中Fuel_Id ='& txtfillingid.Text& '，GenID ='& txtGeneratorId.Text& '，F_date ='& txtDate.Text& '，S_F_reading ='& txtBeforefilling.Text& '，E_F_reading ='& txtAfterfilling.Text& '，Total_Feul ='& TxtTottal.Text& '

lblmessage.Text =您的数据已成功删除



'对于每个p作为SqlParameter在Cmd.Parameters中

'Cmd.Parameters.Remove（p）

'Next

Catch ex As Exception

lblmessage.Text = ex .ToString



最后

Con.Close（）

结束尝试



btnInsert.Visible = False

结束Sub

解决方案

首先，不要这样做！不要连接字符串以构建SQL命令。它让您对意外或故意的SQL注入攻击持开放态度，这可能会破坏您的整个数据库。改为使用参数化查询。



第二，逗号不是WHERE条件连接：你需要AND或OR：

  DELETE   FROM  MyTable  WHERE  columnName1 = value  AND  columnName2 = otherValue 

或

  DELETE   FROM  MyTable  WHERE  columnName1 = value ORcolumnName2 = otherValue 

最后，你需要执行命令：

 Cmd.ExecuteNonQuery（）

kindly help me when i tried to delete message show of success but in reality it not perform action of deletion

What I have tried:

Protected Sub btndelete_Click(sender As Object, e As EventArgs) Handles btndelete.Click

Con = New SqlConnection("Data Source=VU-IT-INTERN1;Initial Catalog=fuelsystem;User ID=sa;Password=123")

Try
Con.Open()
Cmd.Connection = Con
Cmd = New SqlCommand
Cmd.CommandText = "DELETE FROM fuel Where Fuel_Id='" & txtfillingid.Text & "', GenID='" & txtGeneratorId.Text & "', F_date='" & txtDate.Text & "', S_F_reading='" & txtBeforefilling.Text & "', E_F_reading='" & txtAfterfilling.Text & "', Total_Feul='" & TxtTottal.Text & "'"
lblmessage.Text = "Your data has succesfully deleted"

'For Each p As SqlParameter In Cmd.Parameters
' Cmd.Parameters.Remove(p)
'Next
Catch ex As Exception
lblmessage.Text = ex.ToString

Finally
Con.Close()
End Try

btnInsert.Visible = False
End Sub

解决方案

Firstly, don't do it like that! Do not concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.

And second, comma is not a WHERE condition conjunction: you need AND or OR:

DELETE FROM MyTable WHERE columnName1=value AND columnName2=otherValue

Or

DELETE FROM MyTable WHERE columnName1=value ORcolumnName2=otherValue

Finally, you need to execute the command:

Cmd.ExecuteNonQuery()

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