SQL · Theory

DAYOFWEEK()

← All stacks

Theory

224/439

DAYOFWEEK()

DAYOFWEEK() is simple if you keep it on paper. Ananya uses it for DAYOFWEEK on Ananya's board in a viva board.

For DAYOFWEEK(), the query planner is in play. Don’t blame it until you have traced DAYOFWEEK on Ananya's board.

Skip DAYOFWEEK() and copy-pasting DAYOFWEEK without a dry-run shows up in a viva board.

Use DAYOFWEEK() when DAYOFWEEK on Ananya's board must stay clear. If a simpler SQL step works, use that instead.

DAYOFWEEK() trap — copy-pasting DAYOFWEEK without a dry-run. Ananya loses marks for that every viva.

After DAYOFWEEK(), Ananya should still remember copy-pasting DAYOFWEEK without a dry-run.

Viva for DAYOFWEEK(): what it is → one DAYOFWEEK step Ananya can write from memory → the mistake (copy-pasting DAYOFWEEK without a dry-run).

Exam tip

Say DAYOFWEEK() in one breath, then one DAYOFWEEK step Ananya can write from memory, then copy-pasting DAYOFWEEK without a dry-run.

DAYOFWEEK() — sample query

-- DAYOFWEEK()
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;

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

Short notes

DefDAYOFWEEK() — Ananya uses it for DAYOFWEEK on Ananya's board in a viva board.
RuleDAYOFWEEK() → one DAYOFWEEK step Ananya can write from memory.
RememberDAYOFWEEK() + the query planner (a viva board).
UseDAYOFWEEK() in a viva board (DAYOFWEEK on Ananya's board).
TrapDAYOFWEEK() — copy-pasting DAYOFWEEK without a dry-run.
ExDAYOFWEEK() → DAYOFWEEK on Ananya's board.

-- DAYOFWEEK() 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;

DAYOFWEEK()

DAYOFWEEK() — sample query

Short notes

Questions

DAYOFWEEK()

DAYOFWEEK() — sample query

Short notes

Questions