MS Access multi field search with empty fields - sql

Question

I have a problem very similar to this one, but I just can't seem to solve it!
In MS Access (2003), I want to search a table based on entries in a number of fields, some of which may be empty.
I have:
text fields
date fields
integer fields, and
a memo field (but we can probably not bother searching this one if it is difficult).
They map onto a table exactly.
I am trying to create a query that will return matching rows when data is entered into one or more of these fields, but some fields can be left blank. How the heck do I do this?
A query like the one on the linked question works for text fields, but what do I do about the number fields, date fields (and possibly even the memo field)?
To give a clear example, the following code block works for TextField1, but not NumberField1:
PARAMETERS [Forms]![SearchForm]![FilterTextField1] Text ( 255 ), [Forms]![SearchForm]![FilterNumberField1] Text ( 255 );
SELECT Table1.[TextField1], Table1.[NumberField1], Table1.[TextField2], Table1.[TextField3], Table1.[DateField1], Table1.[DateField2], Table1.[DateField3]
FROM Table1
WHERE (Len([Forms]![SearchForm]![FilterTextField1] & '')=0 OR Table1.[TextField1] Like '*' & [Forms]![SearchForm]![FilterTextField1] & '*') AND (Len([Forms]![SearchForm]![FilterNumberField1] & '')=0 OR Table1.[NumberField1] Like '*' & [Forms]![SearchForm]![FilterNumberField1] & '*');
I do hope you can help. I'm sure I'm missing something really obvious, but for some reason my brain feels like it is leaking out of my ears at the moment.
Thank you!
If you need it, this is the basic design of the relevant entities:
Table1
SomePrimaryKeyWeDontCareAboutRightNow
TextField1
TextField2
TextField3
NumberField1
DateField1
DateField2
DateField3
MemoField1
SearchForm
FilterTextField1
FilterTextField2
FilterTextField3
FilterNumberField1
FilterDateField1
FilterDateField2
FilterDateField3
FilterMemoField1

Answer 1

You can check fo null values or cast to string

Answer 2

You could certainly spend a great deal of time crafting a huge and very hard to debug SQL query for this, or just jump into VBA and write some code to construct just the SQL you need.
VBA is there just for these kinds of scenario, where something is either impossible or becoming too complex to do otherwise.
With VBA, you can use an initial SELECT query that collect all the data, and then construct a WHERE clause based on the content of your search form to filter it.
For instance, I have a form like this, that allows the user to enter any criteria to filter a list of prices:
Some code to implement this could look like:
' Call this whenever the use click the Apply button '
Private Sub btApply_Click()
' Construct the filter '
Dim filter As String
If Not IsBlank(cbSupplierID) Then
If Not IsBlank(filter) Then filter = filter & " AND "
filter = filter & "(SupplierID=" & cbSupplierID & ")"
End If
If Not IsBlank(txtPartNumber) Then
If Not IsBlank(filter) Then filter = filter & " AND "
filter = filter & "(PartNumber LIKE '*" & txtPartNumber & "*')"
End If
If Not ckShowLocked Then
If Not IsBlank(filter) Then filter = filter & " AND "
filter = filter & "(NOT PriceLocked)"
End If
' ... code snipped, you get the jest ... '
' Now re-construct the SQL query '
Dim sql As String
sql = "SELECT * FROM Price"
If Not IsBlank(filter) Then
sql = sql & " WHERE " & filter
End If
SubForm.Form.RecordSource = sql
End Sub
It may seem like a lot of code, but each block only does one thing, and it's a lot easier to debug and maintain than cramming everything into a query.