How can I use sql db2 update function? - sql

Question

I have a sql db2 code that get information on a existing data table and I want to modify it to not download the data starting from 2020-02-01, instead just update this table everyday. Please help me to modify this script not to retrieve the whole data over and over again just to update but keeps on updating only the new data everyday.
create table public.fc_TDPMean_By_DIM2_EtchDate as
select DIM2_EtchDate, Model, tool_id, avg(TDPower) as TDPower_Mean, count(slider_id)
from (select distinct a.slider_id, trunc(a.test_date_time), left(a.product_id,2) as Model, a.wafer_id, a.row_number,
a.column_number, a.x_coordinate, a.y_coordinate, a.error_code, a.grade, a.bin,
a.TFCTDPWR as TDPower, b.job_number, trunc(c.transaction_date_time) as DIM2_EtchDate, c.tool_id
from ah.param_jade_wide a left join ah.param_lap_summary b on a.wafer_id = b.wafer_id and a.row_number = b.row_number
left join ah.his_job c on c.job_number = b.job_number
where c.transaction_date_time > '2020-02-01'
and left(a.product_id,2) in ('L2','L3','L8','C3','C2','V8')
and b.source_system_code in ('MFG2.SLDR.LAPRUN')
and c.operation_id in ('545600')
and a.retest_number = 0
and a.class_description in ('PROD')
and not c.tool_id = 0 and not c.tool_id in ('') )
group by DIM2_EtchDate, Model, tool_id;
commit;

Answer 1

As You want to add a new "day" entry/entries every day (as DIM2_EtchDate == DATE(c.transaction_date_time) is a part of the summary table), and if You are OK with not selecting "today's" entries, You can just use a simple INSERT for "yesterdays and before" entries, run every day like this:
INSERT INTO public.fc_TDPMean_By_DIM2_EtchDate
SELECT DIM2_EtchDate, Model, tool_id, avg(TDPower) AS TDPower_Mean, count(slider_id)
FROM (SELECT DISTINCT a.slider_id, LEFT(a.product_id,2) as Model,
a.TFCTDPWR AS TDPower, TRUNC(c.transaction_date_time) as DIM2_EtchDate, c.tool_id
-- (I got rid of not used columns.)
FROM ah.param_jade_wide a
LEFT JOIN ah.param_lap_summary b ON (a.wafer_id, a.row_number) = (b.wafer_id, b.row_number)
LEFT JOIN ah.his_job c ON c.job_number = b.job_number
WHERE c.transaction_date_time > '2020-02-01' --MAX(DIM2_EtchDate)
AND c.transaction_date_time < CURRENT DATE
AND LEFT(a.product_id,2) IN ('L2','L3','L8','C3','C2','V8')
AND b.source_system_code IN ('MFG2.SLDR.LAPRUN')
AND c.operation_id IN ('545600')
AND a.retest_number = 0
AND a.class_description IN ('PROD')
AND NOT c.tool_id = 0 AND NOT c.tool_id in ('')
)
GROUP BY DIM2_EtchDate, Model, tool_id
-- WITH appropriate isolation
;
(I haven't tested it. This should work if c.transaction_date_time is DATE. If it is TIMESTAMP, then c.transaction_date_time > '2020-02-01' changes to c.transaction_date_time >= TIMESTAMP('2020-02-01', '00:00') + 1 DAY.)
If You would want to update it more often than once per day, having also incomplete data for today, it could be done using MERGE. If so, just tell me, I could manage to write a MERGE for it. (Or You could, that would be better.)