SQL · Theory

Practice Database

Theory

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Practice Database

Practice Database is simple if you keep it on paper. Asha uses it for Practice Database on Asha's board in a small live site.

Do Practice Database once by hand. one Practice Database step Asha can write from memory. Change one input. Say the new result out loud.

Without Practice Database, a small live site gets messy and Practice Database on Asha's board is hard to trust.

Use Practice Database when Practice Database on Asha's board must stay clear. If a simpler SQL step works, use that instead.

Don’t do this with Practice Database — only reciting the name of Practice Database. Interviewers spot it in ten seconds.

Place Practice Database next to nearby SQL work — one Practice Database step Asha can write from memory is the link.

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

Exam tip

Say Practice Database in one breath, then one Practice Database step Asha can write from memory, then only reciting the name of Practice Database.

Practice Database — sample query

-- Practice Database
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;

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

Short notes

DefPractice Database — Asha uses it for Practice Database on Asha's board in a small live site.
RulePractice Database → one Practice Database step Asha can write from memory.
RememberPractice Database + the query planner (a small live site).
UsePractice Database in a small live site (Practice Database on Asha's board).
TrapPractice Database — only reciting the name of Practice Database.
ExPractice Database → Practice Database on Asha's board.

-- Practice Database 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;

Practice Database

Practice Database — sample query

Short notes

Questions

Practice Database

Practice Database — sample query

Short notes

Questions