SQL · Theory

Alias

Theory

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Alias

Alias is a SQL idea you prove with Farhan walking through Alias, not with a slogan.

Alias on the board: one Alias step Farhan can write from memory. Then say what Farhan walking through Alias looks like after.

Alias exists so Farhan can keep Farhan walking through Alias correct in lab hour.

Use Alias when Farhan walking through Alias must stay clear. If a simpler SQL step works, use that instead.

Alias trap — skipping the failure case for Alias. Farhan loses marks for that every viva.

Alias is not a lonely heading. Farhan ties it to Farhan walking through Alias.

Viva for Alias: what it is → one Alias step Farhan can write from memory → the mistake (skipping the failure case for Alias).

Exam tip

For Alias: definition + lab hour + one failure.

Alias — sample query

-- Alias
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;

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

Short notes

DefAlias — Farhan uses it for Farhan walking through Alias in lab hour.
RuleAlias → one Alias step Farhan can write from memory.
RememberAlias + an index (lab hour).
UseAlias in lab hour (Farhan walking through Alias).
TrapAlias — skipping the failure case for Alias.
ExAlias → Farhan walking through Alias.

-- Alias 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;

Alias

Alias — sample query

Short notes

Questions

Alias

Alias — sample query

Short notes

Questions