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CASE

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CASE

CASE is a SQL idea you prove with a CASE dry-run, not with a slogan.

Do CASE once by hand. one CASE step Dev can write from memory. Change one input. Say the new result out loud.

Skip CASE and copy-pasting CASE without a dry-run shows up in a first job task.

Dev ships CASE in a first job task. That is the use case worth saying.

CASE trap — copy-pasting CASE without a dry-run. Dev loses marks for that every viva.

Place CASE next to nearby SQL work — one CASE step Dev can write from memory is the link.

One breath for CASE, then a CASE dry-run, then copy-pasting CASE without a dry-run. Sit down.

Exam tip

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

CASE — sample query

-- CASE
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;

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

Short notes

DefCASE — Dev uses it for a CASE dry-run in a first job task.
RuleCASE → one CASE step Dev can write from memory.
RememberCASE + an index (a first job task).
UseCASE in a first job task (a CASE dry-run).
TrapCASE — copy-pasting CASE without a dry-run.
ExCASE → a CASE dry-run.

-- CASE 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;

CASE

CASE — sample query

Short notes

Questions

CASE

CASE — sample query

Short notes

Questions