validate if value is in database [Answered]RSS

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  E.RU

  Member

  44 Points

  155 Posts

  validate if value is in database

  Aug 19, 2019 08:17 AM|E.RU|LINK

  Hi All

  I have a textbox ehich gets results from the database base on the value entered into the textbox.  I am looking to do a validation check. eg. if value entered in textbox is in sql database then write "Error: Invalid Value". I am not sure how to go about this in Vb

  any help would be great

  Thanks

• • Reply
  samwu

  Contributor

  2870 Points

  1200 Posts

  Re: validate if value is in database

  Aug 20, 2019 02:18 AM|samwu|LINK

  Hi E.RU,

  According to your description, I made a demo for your reference.

  You can use Ado.net to query the values in the database, and then compare the values of the textbox with the data that you query.

  The code:

  <div>
              Check from database:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox><br />
              <asp:Button ID="Button1" runat="server" Text="Check" OnClick="Button1_Click" /><br />
              <asp:Label ID="Label1" runat="server"></asp:Label>
          </div>
  
  Private flage As Boolean = False
  
      Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)
          Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
  
          Using con As SqlConnection = New SqlConnection(constr)
  
              Using cmd As SqlCommand = New SqlCommand("SELECT CustomerId FROM Customer where Name='n1'")
                  cmd.Connection = con
                  con.Open()
                  Dim sdr As SqlDataReader = cmd.ExecuteReader()
  
                  While sdr.Read()
  
                      If sdr(0).ToString() = TextBox1.Text Then
                          flage = True
                          Exit While
                      End If
                  End While
  
                  If flage = True Then
                      Label1.Text = "Invalid Value"
                  Else
                      Label1.Text = "valid Value"
                  End If
              End Using
          End Using
  End Sub
  

  The result:

  

  Best regards,

  Sam

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