SQL · Theory

HEX()()

Theory

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HEX()()

HEX()() (str) sits in a small live site. Dev’s job is Dev walking through HEX str. Write that first.

HEX()() (str) on the board: one HEX str step Dev can write from memory. Then say what Dev walking through HEX str looks like after.

Skip HEX()() (str) and copy-pasting HEX str without a dry-run shows up in a small live site.

HEX()() (str) shows up in a small live site. Name Dev walking through HEX str, not “a real-world scenario”.

If Dev walking through HEX str breaks under HEX()() (str), check copy-pasting HEX str without a dry-run first.

After HEX()() (str), Dev should still remember copy-pasting HEX str without a dry-run.

Close HEX()() (str) with: “If I skip it, Dev walking through HEX str goes wrong like this: copy-pasting HEX str without a dry-run.”

Exam tip

Board: Dev walking through HEX str. Dry-run HEX()() (str). Name the trap: copy-pasting HEX str without a dry-run.

HEX()() — sample query

-- HEX()()
CREATE TABLE demo (
  id INTEGER PRIMARY KEY,
  label TEXT NOT NULL,
  qty INTEGER DEFAULT 0
);
INSERT INTO demo (id, label, qty) VALUES
  (1, 'alpha', 2),
  (2, 'beta', 5);
SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

HEX()(): create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Short notes

DefHEX()() (str) — Dev uses it for Dev walking through HEX str in a small live site.
RuleHEX()() (str) → one HEX str step Dev can write from memory.
RememberHEX()() (str) + an index (a small live site).
UseHEX()() (str) in a small live site (Dev walking through HEX str).
TrapHEX()() (str) — copy-pasting HEX str without a dry-run.
ExHEX()() (str) → Dev walking through HEX str.

-- HEX()() CREATE TABLE demo ( id INTEGER PRIMARY KEY, label TEXT NOT NULL, qty INTEGER DEFAULT 0 ); INSERT INTO demo (id, label, qty) VALUES (1, 'alpha', 2), (2, 'beta', 5); SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

HEX()()

HEX()() — sample query

Short notes

Questions

HEX()()

HEX()() — sample query

Short notes

Questions