SQL · Theory

Change Column Type

Theory

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Change Column Type

Change Column Type is a SQL idea you prove with Change Column Type on Rohit's board, not with a slogan.

Change Column Type order: meaning → one Change Column Type step Rohit can write from memory → one limit. Dumping ten features helps nobody.

Skip Change Column Type and copy-pasting Change Column Type without a dry-run shows up in a viva board.

Change Column Type shows up in a viva board. Name Change Column Type on Rohit's board, not “a real-world scenario”.

Change Column Type miss — copy-pasting Change Column Type without a dry-run. Fix it before you talk about advanced SQL.

Place Change Column Type next to nearby SQL work — one Change Column Type step Rohit can write from memory is the link.

Close Change Column Type with: “If I skip it, Change Column Type on Rohit's board goes wrong like this: copy-pasting Change Column Type without a dry-run.”

Exam tip

Say Change Column Type in one breath, then one Change Column Type step Rohit can write from memory, then copy-pasting Change Column Type without a dry-run.

Change Column Type — sample query

-- Change Column Type
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;

Change Column Type: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Short notes

DefChange Column Type — Rohit uses it for Change Column Type on Rohit's board in a viva board.
RuleChange Column Type → one Change Column Type step Rohit can write from memory.
RememberChange Column Type + an index (a viva board).
UseChange Column Type in a viva board (Change Column Type on Rohit's board).
TrapChange Column Type — copy-pasting Change Column Type without a dry-run.
ExChange Column Type → Change Column Type on Rohit's board.

-- Change Column Type 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;

Change Column Type

Change Column Type — sample query

Short notes

Questions

Change Column Type

Change Column Type — sample query

Short notes

Questions