How to insert NULL into database if form field is empty

Question

I have a form and stored procedure that inserts the data from the form. It works fine except that if a field isn\'t filled in it doesn\'t insert a NULL into SQL

Answer 1

I think you problem is that frmFirstName is a string and a string cannot represent DBNull.

I think this will solve your problem (I've just commented out your code):

Dim rdr As SqlDataReader
            Dim cmdInsert As SqlCommand = New SqlCommand()
            cmdInsert.CommandText = "spPersonalDetailsInsert"
            cmdInsert.CommandType = CommandType.StoredProcedure
            cmdInsert.Connection = connSQL


            Dim firstname, lastname, address, address1, town, county, postcode As SqlParameter
            'convert to null if ""
            Dim frmFirstName As String
            'If pd_first_name.Text = "" Then
            '    frmFirstName = Convert.DBNull
            'Else
            '    frmFirstName = pd_first_name.Text
            'End If

            firstname = New SqlParameter()
            firstname.ParameterName = "@firstname"
            firstname.SqlDbType = SqlDbType.NVarChar
            firstname.Size = 50
            firstname.Direction = ParameterDirection.Input
            If pd_first_name.Text = "" Then
                  firstname.Value = DBNull.Value
            Else
                  firstname.Value = frmFirstName
            End If

Answer 2

While creating stored procedure make those columns as null which can be null.. like

CREATE PROCEDURE [dbo].[USP_TDS_SaveRecod]

@ID INT,

@CODE  INT,

@FIRSTNAME VARCHAR(8)=NULL,

@CITY VARCHAR(15)=NULL

AS

BEGIN

    .........................

    .........................

    .........................
END

and then in code don't add those parameters which are null..

cmd.Parameters.Add("@ID", SqlDbType.Int).Value = obj.ID;
cmd.Parameters.Add("@CODE", SqlDbType.Int).Value = obj.CODE;
if(pd_first_name.Text != "")
{
    cmd.Parameters.Add("@FIRSTNAME", SqlDbType.VarChar).Value = pd_first_name.Text;
}
if(city.Text != "")
{
    cmd.Parameters.Add("@CITY", SqlDbType.VarChar).Value = pd_first_name.Text;
}

Answer 3

If RdFree.Checked = True Then
    Dim nu As String = "NULL"
    UpdPolicys.Append(", AccIDFree = " & nu & " , AccTypeIDFree = " & nu & " ")
End If

Answer 4

why you even set it if it is null?

        If pd_first_name.Text <> "" Then
          frmFirstName = pd_first_name.Text
          firstname = New SqlParameter()
          firstname.ParameterName = "@firstname"
          firstname.SqlDbType = SqlDbType.NVarChar
          firstname.Size = 50
          firstname.Direction = ParameterDirection.Input
          firstname.Value = frmFirstName
        End If

Answer 5

You need to use DBNull.Value

            If String.IsNullOrEmpty(pd_first_name.Text.ToString().Trim) = true Then
                frmFirstName = DBNull.Value
            Else
                frmFirstName = pd_first_name.Text
            End If

Answer 6

Dim TempStr As String
TempStr= "spPersonalDetailsInsert"
TempStr = TempStr.Replace("''", "null")
cmdInsert.CommandText = TempStr

Now No Need to use

If pd_first_name.Text = "" Then
   Response.Write("NULL")
   address1.Value = DBNull.Value
Else
   Response.Write("NOT NULL")
   address1.Value = pd_address1.Text
End If 

Hope this might be Helpful