Re: Is it possible to create a sub select where the sub select refreshes itself for each record read?

@Niels, Thanks.
@Darren, the subselect is done once before the select is processed. It does
not go back and check for added records.

Darryl


On Mon, Apr 17, 2023 at 12:50 PM Darren Strong <darren@xxxxxxxxx> wrote:

Performance and reliability would be better if you wrote the query to
avoid the duplicates to begin with. I added a "distinct" to the selection
below. You could also use "group by" instead.

Insert into Table_B (Field_A)
Select distinct(field_a)
From Table_A
Where Field_A not in (select * from table_b)

INSERT into TABLE_B (FIELD_A)
(SELECT distinct(FIELD_A)
from TABLE_A
where FIELD_A not in (Select Field_A from TABLE_B)

-----Original Message-----
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of
Niels Liisberg
Sent: Monday, April 17, 2023 11:39 AM
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: Is it possible to create a sub select where the sub select
refreshes itself for each record read?

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Yes - but you have to use a MERGE INTO ....

On Mon, Apr 17, 2023 at 5:37 PM a4g atl <a4ginatl2@xxxxxxxxx> wrote:

This is one I always need.

I am reading table_A and need to check if the record exists in TABLE_B.
If it does not exist in tableB, I need to add it to table_B.

Problem is this will generate duplicate records.

Is there a way to have the sub select refresh itself before the next
SELECT is executed? I would like the sub select to be dynamic and
sensitive to each insert.

Example:
INSERT into TABLE_B (FIELD_A)
(SELECT FIELD_A
from TABLE_A
where FIELD_A not in (Select Field_A from TABLE_B)

TIA, Darryl Freinkel.
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