SQL · Theory

DATE_ADD()

Theory

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DATE_ADD()

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

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

Skip DATE_ADD() and only reciting the name of DATE_ADD shows up in a campus project.

Meera ships DATE_ADD() in a campus project. That is the use case worth saying.

Don’t do this with DATE_ADD() — only reciting the name of DATE_ADD. Interviewers spot it in ten seconds.

After DATE_ADD(), Meera should still remember only reciting the name of DATE_ADD.

One breath for DATE_ADD(), then a DATE_ADD dry-run, then only reciting the name of DATE_ADD. Sit down.

Exam tip

Board: a DATE_ADD dry-run. Dry-run DATE_ADD(). Name the trap: only reciting the name of DATE_ADD.

DATE_ADD() — sample query

-- DATE_ADD()
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;

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

Short notes

DefDATE_ADD() — Meera uses it for a DATE_ADD dry-run in a campus project.
RuleDATE_ADD() → one DATE_ADD step Meera can write from memory.
RememberDATE_ADD() + the query planner (a campus project).
UseDATE_ADD() in a campus project (a DATE_ADD dry-run).
TrapDATE_ADD() — only reciting the name of DATE_ADD.
ExDATE_ADD() → a DATE_ADD dry-run.

-- DATE_ADD() 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;

DATE_ADD()

DATE_ADD() — sample query

Short notes

Questions

DATE_ADD()

DATE_ADD() — sample query

Short notes

Questions