I'm looking for a way to filter and delete records after import

Can you explain your needs with more detail?

"importing records into fields???"

I'm not an expert but I'll do my best.

I created a simple table TABLE1 with the following fields:
N - type number
Name - Type text
Flag - Type Yes/No
filled with the following records:
10 John Yes
20 Lewis No
30 Mary No
40 Peter No
50 Paul Yes

Records 10 and 50 are supposed to be deleted because they have the Flag field marked "yes".

The following statement will delete those records:
delete select TABLE1 where Flag = true ;

And you get only:
20 Lewis No
30 Mary No
40 Peter No

So you could:
1. have in your excel files a column to mark those fields you want to delete after import.
2. create in your table a YES/NO field.
3. import your records.
4. Create a Form View and add a Button to this view.
5. In the "On click" box of the button insert the code to delete records marked with yes.
6. Any time you Click the button all records with a "yes" on the Flag field will be deleted.

Or, instead of creating a View and a button, you could simply run the above delete command from the Console.

I think this is what you need.
Perhaps someone can have a better suggestion.

Did you look at the Delete records section here??

https://ninoxdb.de/en/manual/calculations/reference-of-functions-and-language

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