RLIKE — SQL Technical Interview Questions & Answers

RLIKE

RLIKE

  • RLIKE is pattern matching. LIKE uses % and _. REGEXP / RLIKE uses regular expressions (e.g. name REGEXP '^[A-Z]'). They are not interchangeable.
  • REGEXP_LIKE, REGEXP_REPLACE, REGEXP_SUBSTR, REGEXP_INSTR are MySQL 8 helpers. Don’t write Java-style /pattern/g.
  • Trap: LIKE with regex stars. Trap: REGEXP on a huge unindexed column.
  • On the example next to this theory: RLIKE: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Technical Interview Tip: LIKE vs REGEXP in one sentence, plus one example.

Code Examples for RLIKE

RLIKE — sample query

-- RLIKE
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;

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

How to Explain RLIKE to an Interviewer

LIKE vs REGEXP?

LIKE is % and _ REGEXP is regular expressions