IN — SQL Technical Interview Questions & Answers

IN

IN

  • IN is OR for a list. WHERE city IN ('Pune','Goa','Delhi'); NOT IN is the opposite — beware NULL inside NOT IN (the whole test can become unknown).
  • IN (SELECT city FROM allowed) is a subquery form. For a joinable list, a table + JOIN is often clearer.
  • Trap: IN vs =. = is one value. Trap: NOT IN (1, NULL) surprises.
  • On the example next to this theory: IN: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Technical Interview Tip: WHERE city IN ('Pune','Goa');

Code Examples for IN

IN — sample query

-- IN
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;

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

How to Explain IN to an Interviewer

Write IN for two cities.

WHERE city IN ('Pune','Goa')