SQL · Theory

From_days()

Theory

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From_days()

If you can teach From_days() using From_days on Amit's board, you know it. If you only know the heading, you don’t.

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

Without From_days(), lab hour gets messy and From_days on Amit's board is hard to trust.

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

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

After From_days(), Amit should still remember copy-pasting From_days without a dry-run.

One breath for From_days(), then From_days on Amit's board, then copy-pasting From_days without a dry-run. Sit down.

Diagram

  FROM students
        │
        ▼
  WHERE city = 'Pune'
        │
        ▼
  SELECT name, marks

Exam tip

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

From_days() — sample query

-- From_days()
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;

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

Short notes

DefFrom_days() — Amit uses it for From_days on Amit's board in lab hour.
RuleFrom_days() → one From_days step Amit can write from memory.
RememberFrom_days() + InnoDB (lab hour).
UseFrom_days() in lab hour (From_days on Amit's board).
TrapFrom_days() — copy-pasting From_days without a dry-run.
ExFrom_days() → From_days on Amit's board.

-- From_days() 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;

From_days()

From_days() — sample query

Short notes

Questions

From_days()

From_days() — sample query

Short notes

Questions