SQL · Theory

ADDTIME()

Theory

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ADDTIME()

If you can teach ADDTIME() using Sara walking through ADDTIME, you know it. If you only know the heading, you don’t.

ADDTIME() order — meaning → one ADDTIME step Sara can write from memory → one limit. Dumping ten features helps nobody.

ADDTIME() exists so Sara can keep Sara walking through ADDTIME correct in a campus project.

Use ADDTIME() when Sara walking through ADDTIME must stay clear. If a simpler SQL step works, use that instead.

If Sara walking through ADDTIME breaks under ADDTIME(), check only reciting the name of ADDTIME first.

After ADDTIME(), Sara should still remember only reciting the name of ADDTIME.

Close ADDTIME() with: “If I skip it, Sara walking through ADDTIME goes wrong like this: only reciting the name of ADDTIME.”

Exam tip

Say ADDTIME() in one breath, then one ADDTIME step Sara can write from memory, then only reciting the name of ADDTIME.

ADDTIME() — sample query

-- ADDTIME()
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;

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

Short notes

DefADDTIME() — Sara uses it for Sara walking through ADDTIME in a campus project.
RuleADDTIME() → one ADDTIME step Sara can write from memory.
RememberADDTIME() + an index (a campus project).
UseADDTIME() in a campus project (Sara walking through ADDTIME).
TrapADDTIME() — only reciting the name of ADDTIME.
ExADDTIME() → Sara walking through ADDTIME.

-- ADDTIME() 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;

ADDTIME()

ADDTIME() — sample query

Short notes

Questions

ADDTIME()

ADDTIME() — sample query

Short notes

Questions