PostgreSQL-Query tricks

You need those users which entered their name and it is not null. Note that NULL in SQL means no data is provided, So NULL does not means empty string, 0 or anything else. NULL is no data.

select id, first_name from main.user where first_name like '%';        

In other words the following query is the equivalent of former query:

select id, first_name from main.user where first_name is not null;        

TBH I do not have any idea which one is better but I guess the second one is better from performance point of view:

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Do not use * wild card in the select statement

It is not a good practice, especially for prod apps. BTW TBH I done it in my past. But now I do not do that.

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How PostgreSQL saves timezone when you said that save with UTC?

• UTC = 00:00 timezone

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order by

• ASC means from small to big
• DESC means from big to small

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To be continued ...