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Even for data transformation logic, SQL isn’t the best choice. How would you handle the case when you need to apply the same transformations to few dozens or hundreds columns?

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Some SQL engines support generating and evaluating queries. I stumbled upon a function in MariaDB code base that is introduced and keps specifically for that use case (it returns properly quoted SQL value as a string, including "NULL" string for null values). It is aptly named QUOTE [1].

[1] https://mariadb.com/kb/en/quote/

You can then specify columns as a query, group_concat the result and evaluate resulting statement [2].

https://mariadb.com/kb/en/execute-immediate/

I hope that helps.

I'm not sure I understand the question, you can create tables/views based on others that have the transformations applied to them, tools like dbt[1] make this easy.

[1]: https://www.getdbt.com/

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