I've got a question about DBLookupComboBox.

I've got a program which has a database I authored. It's everything, except after i open DBLookupComboBox it has to possess a row with null value when ever user really wants to choose nothing. But there is not one. How do i create a null row appear?

You have to either give a row that states 'Nothing' or 'All', no matter which suits. The typical option would be a UNION query, which can be used the RowSource from the combobox. The Union query may be used to add virtual fields.

When the combo comtains only unique values, you are able to say:

SELECT "Nothing" As Description
FROM ATable
UNION 
SELECT Description
FROM ATable

UNION removes replicates, UNION ALL< doesn't, therefore if you will find matching rows, you are able to say:

SELECT DISTINCT "Nothing" As Description
FROM ATable
UNION ALL
SELECT Description
FROM ATable

If you would like "Nothing" to sort first, you have to juggle just a little and employ " Nothing", or "-Nothing", but when you possess an ID or Key column you can aquire a nice sort, like so:

SELECT 0 As ID, "Nothing" As Description
FROM ATable
UNION 
SELECT ID, Description
FROM ATable