SQL · Theory

Stored

Theory

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Stored

Stored programs in MySQL: procedures, functions, triggers, events. They live in the database. The CLI needs a different DELIMITER to define them.

Functions — SELECT fn(marks). Procedures: CALL. Triggers: automatic. Events: scheduled (like a cron inside MySQL).

Trap — ‘stored’ as a vague word without saying which of the four.

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

Exam tip

Four stored objects. DELIMITER when you CREATE them.

Stored — sample query

-- Stored
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;

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

Short notes

DefStored programs = procedure, function, trigger, event.
RuleCALL vs SELECT vs automatic vs schedule.
TrapMixing procedure and function.

-- Stored 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;

Stored

Stored — sample query

Short notes

Questions

Stored

Stored — sample query

Short notes

Questions