SQL · Theory

Pivot Table

Theory

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Pivot Table

Meera only reaches for Pivot Table when a Pivot Table dry-run has to stay correct in a first job task.

Do Pivot Table once by hand. one Pivot Table step Meera can write from memory. Change one input. Say the new result out loud.

Without Pivot Table, a first job task gets messy and a Pivot Table dry-run is hard to trust.

Meera ships Pivot Table in a first job task. That is the use case worth saying.

Pivot Table trap — skipping the failure case for Pivot Table. Meera loses marks for that every viva.

Pivot Table is not a lonely heading. Meera ties it to a Pivot Table dry-run.

One breath for Pivot Table, then a Pivot Table dry-run, then skipping the failure case for Pivot Table. Sit down.

Exam tip

Board: a Pivot Table dry-run. Dry-run Pivot Table. Name the trap: skipping the failure case for Pivot Table.

Pivot Table — sample query

-- Pivot 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;

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

Short notes

DefPivot Table — Meera uses it for a Pivot Table dry-run in a first job task.
RulePivot Table → one Pivot Table step Meera can write from memory.
RememberPivot Table + an index (a first job task).
UsePivot Table in a first job task (a Pivot Table dry-run).
TrapPivot Table — skipping the failure case for Pivot Table.
ExPivot Table → a Pivot Table dry-run.

-- Pivot 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;

Pivot Table

Pivot Table — sample query

Short notes

Questions

Pivot Table

Pivot Table — sample query

Short notes

Questions