September 2024
Intermediate to advanced
400 pages
10h 11m
German
Content preview from Snowflake SQL und Skripting lernen
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
Kapitel 8. Unterabfragen
Diese Arbeit wurde mithilfe von KI übersetzt. Wir freuen uns über dein Feedback und deine Kommentare: translation-feedback@oreilly.com
Unterabfragen sind ein mächtiges Werkzeug, das in den Anweisungen select, update, insert, delete und merge verwendet werden kann. In diesem Kapitel lernst du die verschiedenen Arten von Unterabfragen kennen und erfährst, wie sie mit deinen SQL-Anweisungen interagieren können.
Definierte Unterabfragen
Eine Subquery ist eine Abfrage, die in einer anderen SQL Anweisung enthalten ist (im weiteren Verlauf dieses Kapitels als Containing Statement oder Containing Query bezeichnet). Unterabfragen sind immer von Klammern umgeben und werden in der Regel vor der enthaltenden Anweisung ausgeführt. Wie jede Abfrage liefert auch die Unterabfrage eine Ergebnismenge, die aus einer oder mehreren Zeilen und einer oder mehreren Spalten bestehen kann. Der Typ der von der Subquery zurückgegebenen Ergebnismenge bestimmt, welche Operatoren die enthaltende Anweisung verwenden kann, um mit den von der Subquery zurückgegebenen Daten zu interagieren.
Hier ist ein einfaches Beispiel, um den Einstieg zu erleichtern:
PUBLIC>select n_nationkey, n_name from nation
where n_regionkey =
(select r_regionkey from region where r_name = 'ASIA'); +-------------+-----------+ | N_NATIONKEY | N_NAME | |-------------+-----------| | 8 | INDIA | | 9 | INDONESIA | | 12 | JAPAN | | 18 | CHINA | | 21 ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.