To close this book on a lighter note but with wisdom anyway, here are some proverbs.
(As Lili said:) Trash in ! trash out ! Meaning if you do not put in the maximum care when you import data, you will get the data you deserve as query results!
Take care of the nulls, do not import numbers as strings, and use booleans when needed.
Everything is misplaced when you mistake latitude and longitude!
Having one's child's name on a book cover makes family happy!
The joy of learning calls for the joy to teach!
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