SQL · Theory

regexp_replace()

Theory

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regexp_replace()

Meera only reaches for regexp_replace() when a regexp_replace dry-run has to stay correct in a first job task.

Do regexp_replace() once by hand. one regexp_replace step Meera can write from memory. Change one input. Say the new result out loud.

Without regexp_replace(), a first job task gets messy and a regexp_replace dry-run is hard to trust.

regexp_replace() shows up in a first job task. Name a regexp_replace dry-run, not “a real-world scenario”.

regexp_replace() miss — only reciting the name of regexp_replace. Fix it before you talk about advanced SQL.

After regexp_replace(), Meera should still remember only reciting the name of regexp_replace.

Viva for regexp_replace(): what it is → one regexp_replace step Meera can write from memory → the mistake (only reciting the name of regexp_replace).

Exam tip

For regexp_replace(): definition + a first job task + one failure.

regexp_replace() — sample query

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

Short notes

Defregexp_replace() — Meera uses it for a regexp_replace dry-run in a first job task.
Ruleregexp_replace() → one regexp_replace step Meera can write from memory.
Rememberregexp_replace() + the query planner (a first job task).
Useregexp_replace() in a first job task (a regexp_replace dry-run).
Trapregexp_replace() — only reciting the name of regexp_replace.
Exregexp_replace() → a regexp_replace dry-run.

-- regexp_replace() 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_replace()

regexp_replace() — sample query

Short notes

Questions

regexp_replace()

regexp_replace() — sample query

Short notes

Questions