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second()

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second()

second() is simple if you keep it on paper. Sara uses it for a second dry-run in lab hour.

For second(), the query planner is in play. Don’t blame it until you have traced a second dry-run.

Skip second() and skipping the failure case for second shows up in lab hour.

Sara ships second() in lab hour. That is the use case worth saying.

second() miss — skipping the failure case for second. Fix it before you talk about advanced SQL.

Place second() next to nearby SQL work — one second step Sara can write from memory is the link.

Close second() with — “If I skip it, a second dry-run goes wrong like this: skipping the failure case for second.”

Exam tip

Board: a second dry-run. Dry-run second(). Name the trap: skipping the failure case for second.

second() — sample query

-- second()
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;

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

Short notes

Defsecond() — Sara uses it for a second dry-run in lab hour.
Rulesecond() → one second step Sara can write from memory.
Remembersecond() + the query planner (lab hour).
Usesecond() in lab hour (a second dry-run).
Trapsecond() — skipping the failure case for second.
Exsecond() → a second dry-run.

-- second() 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;

second()

second() — sample query

Short notes

Questions

second()

second() — sample query

Short notes

Questions