How to set a NULL value through the VCL

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Question:

I need to set a field in a record back to NULL (not an empty string or 0 for a numeric field).
I know I could run a SQL statement and do something like

'update customers set pid = NULL where cust_id=1234'

How can I do this within a TQuery using .Edit and .Post methods and TField instances to assign values?

Answer:

To set a field to NULL, you need to use the TField.Clear method. See the code below for an example.

	var Query1 : TQuery; begin //.. Query1.Edit; Query1.FieldByName('FIRST_NAME').AsString = 'noname'; Query1.FieldByName('P_ID').Clear; // set this field to NULL Query1.Post; end

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