sql – Help! How does this select work

Question:

Help me understand how this works please.

It turns out that I'm starting studies in SQL and hackerhank has an exercise that needed this code:

SELECT DISTINCT CITY FROM STATION WHERE REGEXP_LIKE(LOWER(CITY), '^[aeiou]') ;

After a lot of effort and someone helped me, as I had gone to a little more than half of this select and the end in my head I knew what to do, but without technical knowledge it is difficult to write.

Can someone translate what the code is doing so I can assimilate.

Answer:

  • FROM STATION selects data from the STATION table;
  • LOWER(CITY) will compare the CITY column with the lowercase letter;
  • REGEXP_LIKE(..., '^[aeiou]') compares if they start with vowels;
  • DISTINCT does not show duplicate results;

In other words: Selects all CITY from the STATION table, without repetition, that start with vowels in the name;

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