SQL · Theory

regexp_like()

Theory

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regexp_like()

If you can teach regexp_like() using a regexp_like dry-run, you know it. If you only know the heading, you don’t.

regexp_like() on the board: one regexp_like step Amit can write from memory. Then say what a regexp_like dry-run looks like after.

Skip regexp_like() and skipping the failure case for regexp_like shows up in a first job task.

Use regexp_like() when a regexp_like dry-run must stay clear. If a simpler SQL step works, use that instead.

If a regexp_like dry-run breaks under regexp_like(), check skipping the failure case for regexp_like first.

regexp_like() is not a lonely heading. Amit ties it to a regexp_like dry-run.

One breath for regexp_like(), then a regexp_like dry-run, then skipping the failure case for regexp_like. Sit down.

Exam tip

Say regexp_like() in one breath, then one regexp_like step Amit can write from memory, then skipping the failure case for regexp_like.

regexp_like() — sample query

-- regexp_like()
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;

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

Short notes

Defregexp_like() — Amit uses it for a regexp_like dry-run in a first job task.
Ruleregexp_like() → one regexp_like step Amit can write from memory.
Rememberregexp_like() + the query planner (a first job task).
Useregexp_like() in a first job task (a regexp_like dry-run).
Trapregexp_like() — skipping the failure case for regexp_like.
Exregexp_like() → a regexp_like dry-run.

-- regexp_like() 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;

regexp_like()

regexp_like() — sample query

Short notes

Questions

regexp_like()

regexp_like() — sample query

Short notes

Questions