Update pipeline.rst - Fix query in merge_data() task

[tsoud]

The alias for the subquery was missing in the merge_data() function's query, so it just needed to be added. Otherwise, the employees table remains empty. I found the error in the postgres container logs:

2023-01-25 08:00:03 2023-01-25 14:00:03.256 UTC [70428] ERROR:  subquery in FROM must have an alias at character 74
2023-01-25 08:00:03 2023-01-25 14:00:03.256 UTC [70428] HINT:  For example, FROM (SELECT ...) [AS] foo.
2023-01-25 08:00:03 2023-01-25 14:00:03.256 UTC [70428] STATEMENT:  
2023-01-25 08:00:03                 INSERT INTO employees
2023-01-25 08:00:03                 SELECT *
2023-01-25 08:00:03                 FROM (
2023-01-25 08:00:03                     SELECT DISTINCT *
2023-01-25 08:00:03                     FROM employees_temp
2023-01-25 08:00:03                 )
2023-01-25 08:00:03                 ON CONFLICT ("Serial Number") DO UPDATE
2023-01-25 08:00:03                 SET "Serial Number" = excluded."Serial Number";

Thank you!

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[boring-cyborg]

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[josh-fell]

The issue with the merge SQL looks to be fixed with the 2.5.1 tutorial. The example is not practical to begin with though. Better to change it.

[boring-cyborg]

Awesome work, congrats on your first merged pull request!

[josh-fell]

@tsoud Congrats on your first contribution! 🎉