Essentiële SQL
SQL toepassen op problemen uit de praktijk
Dmitriy (Dima) Gorenshteyn
Lead Data Scientist, Memorial Sloan Kettering Cancer Center
Wat je gaat leren
- Hoofdstuk 1: SQL in de praktijk
- Hoofdstuk 2: Vind je data
- Hoofdstuk 3: Beheer je data
- Hoofdstuk 4: Best practices voor SQL schrijven
De database
- DVD-verhuurbedrijf
- Gebaseerd op de pagila-database $^1$
| Tabellen | |
|---|---|
| actor | film_actor |
| address | inventory |
| category | language |
| customer | payment |
| film | rental |
Copyright (c) Devrim Gündüz <[email protected]>
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
documentation files (the "Software"), to deal in the Software without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of
the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
1 https://github.com/devrimgunduz/pagila
Essentiële SQL-commando's
SELECT title, length
FROM film AS f
INNER JOIN category AS c
ON f.film_id = c.film_id
WHERE c.category = 'Documentary'
AND f.rating IN ('G', 'PG')
ORDER BY length DESC;
SELECT, FROM
SELECT title, length
FROM film
;
SELECT
SELECT <column1>, <column2>
-- OR
SELECT *
FROM
FROM <table_name>
INNER JOIN
SELECT title, length
FROM film AS f
INNER JOIN category AS c
ON f.film_id = c.film_id
;
AS
<column_name> AS <alias1>
INNER JOIN
INNER JOIN <table_name> AS <alias2>
ON
ON <alias1>.<column> = <alias2>.<column>
WHERE, AND, IN
SELECT title, length
FROM film AS f
INNER JOIN category AS c
ON f.film_id = c.film_id
WHERE c.category = 'Documentary'
AND f.rating IN ('G', 'PG')
;
WHERE
WHERE <condition>
AND
AND <condition>
IN
IN ('<item1>', '<item2>', ...)
ORDER BY, DESC
SELECT title, length
FROM film AS f
INNER JOIN category AS c
ON f.film_id = c.film_id
WHERE c.category = 'Documentary'
AND f.rating IN ('G', 'PG')
ORDER BY length DESC;
ORDER BY
ORDER BY <column_name>
DESC
ORDER BY <column_name> DESC
Oefen de basis!
SQL toepassen op problemen uit de praktijk
