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computer-science/hash-tables-how-a-computer-finds-one-name-among-thousands-without-chec.md
Hash tables: how a computer finds one name among thousands without checking them all
Your phone finds one contact among thousands without reading them all. The trick is a hash table: a row of numbered slots and a small…
databases/sql-joins-how-two-tables-become-one-answer-inner-left-right-full.md
SQL JOINs: how two tables become one answer (INNER, LEFT, RIGHT, FULL)
Your data lives in two tables, but your question needs both. A JOIN lines them up, and the four kinds (INNER, LEFT, RIGHT, FULL) differ…
computer-science/hash-tables-how-python-finds-a-key-without-searching-for-it.md
Hash tables: how Python finds a key without searching for it
You type `ages["cat"]` and Python answers instantly, even with a million entries. It does not search. It calculates where "cat" must be…
databases/why-databases-split-your-data-into-two-tables-and-link-them-by-id.md
Why databases split your data into two tables (and link them by id)
A database table looks like a spreadsheet: columns for each kind of information, one row per thing. But it comes with rules. Every column…