Joining data without creating duplicate metric rows from the first table, (second table contains more rows but not metrics) - postgresql

Question

I have the following two tables that I would like to join for a comprehensive digital marketing report without creating duplicates in regards to metrics. The idea is to take competitor adverts and join them with my existing marketing data which is as follows;
Campaign|Impressions | Clicks | Conversions | CPC |Key
---------+------------+--------+-------------+-----+----
USA-SIM|53432 | 5001 | 5| 2$ |Hgdy24
DE-SIM |5389 | 4672 | 3| 4$ |dhfg12
The competitor data is as follows;
Key | Ad Copie |
---------+------------+
Hgdy24 |Click here! |
Hgdy24 |Free Trial! |
Hgdy24 |Sign Up now |
dhfg12 |Check it out|
dhfg12 |World known |
dhfg12 |Sign up |
Using conventional join queries produces the following unusable result
Campaign|Impressions | Clicks | Conversions | CPC |Key |Ad Copie
---------+------------+--------+-------------+-----+------+---------
USA-SIM|53432 | 5001 | 5| 2$ |Hgdy24|Click here!
USA-SIM|53432 | 5001 | 5| 2$ |Hgdy24|Free Trial!
USA-SIM|53432 | 5001 | 5| 2$ |Hgdy24|Sign Up now
DE-SIM |5389 | 4672 | 3| 4$ |dhfg12|Check it out
DE-SIM |5389 | 4672 | 3| 4$ |dhfg12|World known
DE-SIM |5389 | 4672 | 3| 4$ |dhfg12|Sign up
Here is the desired output
Campaign|Impressions | Clicks | Conversions | CPC |Key |Ad Copie
---------+------------+--------+-------------+-----+------+---------
USA-SIM|53432 | 5001 | 5| 2$ |Hgdy24|Click here!
USA-SIM| | | | |Hgdy24|Free Trial!
USA-SIM| | | | |Hgdy24|Sign Up now
DE-SIM |5389 | 4672 | 3| 4$ |dhfg12|Check it out
DE-SIM | | | | |dhfg12|World known
DE-SIM | | | | |dhfg12|Sign up
Or as an alternative that would also work would be
Campaign|Impressions | Clicks | Conversions | CPC |Key |Ad Copie
---------+------------+--------+-------------+-----+------+---------
USA-SIM|53432 | 5001 | 5| 2$ |Hgdy24|
USA-SIM| | | | |Hgdy24|Click here!
USA-SIM| | | | |Hgdy24|Free Trial!
USA-SIM| | | | |Hgdy24|Sign Up now
DE-SIM |5389 | 4672 | 3| 4$ |dhfg12|
DE-SIM | | | | |dhfg12|Check it out
DE-SIM | | | | |dhfg12|World known
DE-SIM | | | | |dhfg12|Sign up
I have yet to find a work around that does not produce the extra metrics as a result.
MOST RECENT RESULT
campaing | impressions | clicks | conversions | cpc | key | ad_copie
----------+-------------+--------+-------------+-----+--------+------------
USA-SIM | 53432 | 5001 | 5 | 2$ | |
USA-SIM | | | | | Hgdy24 | Click here!
USA-SIM | | | | | Hgdy24 | Free Trial!
USA-SIM | | | | | Hgdy24 | Sign Up now
DE-SIM | 5389 | 4672 | 3 | 4$ | |
DE-SIM | | | | | dhfg12 | Check it out
DE-SIM | | | | | dhfg12 | World known
DE-SIM | | | | | dhfg12 | Sign up

Answer 1

You can use window function lag() to check what key was in previous row and either display metrics or null them.
select campaing,
case when prev_key is null or prev_key != key then impressions end as impressions,
case when prev_key is null or prev_key != key then clicks end as clicks,
case when prev_key is null or prev_key != key then conversions end as conversions,
case when prev_key is null or prev_key != key then cpc end as cpc,
key, ad_copie
from (
select campaing, lag(key) over () AS prev_key, impressions, clicks, conversions, cpc, key, ad_copie
from ad1
join comp1 using(key)
order by campaing desc, key
) sub;
result:
campaing | impressions | clicks | conversions | cpc | key | ad_copie
----------+-------------+--------+-------------+-----+--------+--------------
USA-SIM | 53432 | 5001 | 5 | 2$ | Hgdy24 | Click here!
USA-SIM | | | | | Hgdy24 | Free Trial!
USA-SIM | | | | | Hgdy24 | Sign Up now
DE-SIM | 5389 | 4672 | 3 | 4$ | dhfg12 | Check it out
DE-SIM | | | | | dhfg12 | World known
DE-SIM | | | | | dhfg12 | Sign up
(6 wierszy)
EDIT: You might need to tinker with what columns you compare before you NULL metrics and possibly by what columns you will order data. If key is unique for campaing then I suppose this will suffice.