May 2011
Intermediate to advanced
800 pages
39h 19m
German
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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.
R7.36 Einen Trigger erzeugen und verwenden
Aufgabe
Beim Aktualisieren einer Tabelle soll überprüft werden, ob Übergabewerte bestimmte Grenzen einhalten. Ist dies nicht der Fall, soll ein Fehler ausgelöst werden.
Lösung
Neben der Verwendung von Einschränkungen (CHECK), die jedoch keine möglichen Änderungen an den Daten vornehmen können, bietet sich dafür auch ein Trigger an.
Trigger sind nichts anderes als serverbasierte Ereignisprozeduren, die für drei verschiedene Ereignisse definiert werden können:
Update
Insert
Delete
Worauf Sie mit Ihrem Trigger reagieren, entscheiden Sie innerhalb der Trigger-Routine durch die Angabe der entsprechenden Schlüsselwörter.
Beim Erstellen eines Triggers müssen Sie Folgendes angeben:
Einen Namen
Den Namen der Tabelle, für ...
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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.