SQL · Theory

Temporary Table

Theory

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Temporary Table

CREATE TEMPORARY TABLE tmp_fail AS SELECT * FROM students WHERE marks < 40; lives only for this connection. When you disconnect, it disappears. Other users cannot see it.

Use it for a messy report: filter, join, then SELECT from tmp. Don’t confuse with a normal table of the same name — TEMPORARY hides the real one in that session.

Trap — expecting a temporary table to still be there tomorrow.

On the example next to this theory: Temporary Table: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Exam tip

CREATE TEMPORARY TABLE … — gone when the session ends.

Temporary Table — sample query

-- Temporary Table
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;

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

Short notes

DefTEMPORARY table lasts only for this connection.
RuleGood for intermediate report steps.
TrapThinking it is saved on disk for others.

-- Temporary Table 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;

Temporary Table

Temporary Table — sample query

Short notes

Questions

Temporary Table

Temporary Table — sample query

Short notes

Questions