6.13. SQL Select Where

• Order clauses to filter out the most data first!

6.13.1. Selection

• = - equals

• != - not equal

• <> - not equal

• > - greater then

• >= - greater or equal

• < - less than

• <= - less or equal

SELECT *
FROM astronauts
WHERE lastname = 'Watney';

SELECT *
FROM astronauts
WHERE agency != 'NASA';

SELECT *
FROM astronauts
WHERE age > 30;

6.13.2. Conjunction

• AND - conjunction

SELECT *
FROM astronauts
WHERE lastname = 'Watney'
AND lastname = 'Mark';

SELECT *
FROM astronauts
WHERE age > 30
AND age < 55;

6.13.3. Alternative

• OR - alternative

SELECT *
FROM astronauts
WHERE lastname = 'Watney'
OR lastname = 'Lewis';

6.13.4. Contains

• IN - contains

• NOT IN - not contains

SELECT *
FROM astronauts
WHERE career IN ('Pilot', 'Engineer', 'Scientist', 'Medical Doctor');

SELECT *
FROM astronauts
WHERE lastname NOT IN ('Watney', 'Lewis', 'Martinez');

6.13.5. Identity

• IS - identity check

• IS NOT - negation of an identity check

SELECT *
FROM astronauts
WHERE mission IS NULL;

SELECT *
FROM astronauts
WHERE mission IS NOT NULL;

6.13.6. Like

• LIKE

• % - Any character (many)

• _ - Any character (one)

SELECT *
FROM astronauts
WHERE lastname LIKE 'Wat%';

SELECT *
FROM astronauts
WHERE lastname LIKE '%ney';

SELECT *
FROM astronauts
WHERE lastname LIKE '%tn%';

SELECT *
FROM astronauts
WHERE lastname LIKE 'Watne_';

SELECT *
FROM astronauts
WHERE lastname LIKE '_tn%';