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How to Comment

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How to Comment

-- this is a line comment (space after --). # also works in MySQL. /* block comment */ can span lines.

Don’t put secrets in comments in dumps. Nested /* */ can surprise you.

Trap — --comment without a space after -- in some clients.

On the example next to this theory: How to Comment: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Exam tip

-- comment and /* block */

How to Comment — sample query

-- How to Comment
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;

How to Comment: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Short notes

Def-- and /* */ comments. # in MySQL.
RuleSpace after -- .
TrapPassword in a commented dump line.

-- How to Comment 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;

How to Comment

How to Comment — sample query

Short notes

Questions

How to Comment

How to Comment — sample query

Short notes

Questions