SQL · Theory

localtime()

Theory

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localtime()

If you can teach localtime() using a localtime dry-run, you know it. If you only know the heading, you don’t.

Do localtime() once by hand. one localtime step Sara can write from memory. Change one input. Say the new result out loud.

Without localtime(), a first job task gets messy and a localtime dry-run is hard to trust.

Use localtime() when a localtime dry-run must stay clear. If a simpler SQL step works, use that instead.

localtime() miss — copy-pasting localtime without a dry-run. Fix it before you talk about advanced SQL.

After localtime(), Sara should still remember copy-pasting localtime without a dry-run.

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

Exam tip

For localtime(): definition + a first job task + one failure.

localtime() — sample query

-- localtime()
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;

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

Short notes

Deflocaltime() — Sara uses it for a localtime dry-run in a first job task.
Rulelocaltime() → one localtime step Sara can write from memory.
Rememberlocaltime() + InnoDB (a first job task).
Uselocaltime() in a first job task (a localtime dry-run).
Traplocaltime() — copy-pasting localtime without a dry-run.
Exlocaltime() → a localtime dry-run.

-- localtime() 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;

localtime()

localtime() — sample query

Short notes

Questions

localtime()

localtime() — sample query

Short notes

Questions