SQL · Theory

Data Types

Theory

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Data Types

If you can teach Data Types using a Data Types dry-run, you know it. If you only know the heading, you don’t.

Data Types on the board: one Data Types step Meera can write from memory. Then say what a Data Types dry-run looks like after.

Without Data Types, a campus project gets messy and a Data Types dry-run is hard to trust.

Data Types shows up in a campus project. Name a Data Types dry-run, not “a real-world scenario”.

Data Types trap — copy-pasting Data Types without a dry-run. Meera loses marks for that every viva.

Place Data Types next to nearby SQL work — one Data Types step Meera can write from memory is the link.

Close Data Types with: “If I skip it, a Data Types dry-run goes wrong like this: copy-pasting Data Types without a dry-run.”

Exam tip

Board: a Data Types dry-run. Dry-run Data Types. Name the trap: copy-pasting Data Types without a dry-run.

Data Types — sample query

-- Data Types
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;

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

Short notes

DefData Types — Meera uses it for a Data Types dry-run in a campus project.
RuleData Types → one Data Types step Meera can write from memory.
RememberData Types + an index (a campus project).
UseData Types in a campus project (a Data Types dry-run).
TrapData Types — copy-pasting Data Types without a dry-run.
ExData Types → a Data Types dry-run.

-- Data Types 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;

Data Types

Data Types — sample query

Short notes

Questions

Data Types

Data Types — sample query

Short notes

Questions