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by: Olivier Crèvecoeur |
last post by:
Hello,
Excuse me for my poor english.
I would kike know if create index on the foreign key it's necessary or if
Oracle, are optimized for using foreign key whithout index.
Best regards
Olivier
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by: Bodza Bodza |
last post by:
I'm having an argument with an incumbent self-taught programmer that
it is OK to use null foreign keys in database design.
My take is the whole point of a foreign key is that it's not supposed
to be optional, it's very definition is it's a necessary link to the
parent table and part of the definition. If it's optional it shouldn't
be part of the definition of a table and should be in a linking table
instead.
Comments?
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by: Robert Brown |
last post by:
Let's say I have a type hierarchy: (just an example)
the general entity customer:
CREATE TABLE customer(customer_id int, customer_name varchar(250),
customer_type int)
three specific customer subtypes: 1 - business, 2 - home, 3 -
university
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by: Vinodh Kumar P |
last post by:
I understand the number of foreign keys allowed is restricted by the DBMS I
use.
In a general relational schema design perspective how many foreign keys a
table shall have?
If I have large number of foreign keys what anamolies it will lead to?
Is this crucial to identify all the foriegn key relationships for a table?
Vinodh
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by: Scott Ribe |
last post by:
I've got a problem which I think may be a bug in Postgres, but I wonder if
I'm missing something. Two tables, A & B have foreign key relations to each
other. A 3rd table C, inherits from A. A stored procedure updates a row in
C, adds a row each in B & C. I get an integrity violation. All the foreign
keys are deferrable, and the stored procedure is called from within a
transaction with constraints deferred. (And the foreign keys do refer to...
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by: sonal |
last post by:
Hi all,
I hv started with python just recently... and have been assigned to
make an utility which would be used for data validations...
In short we take up various comma separated data files
for eg: area.txt, school.txt, students.txt.... and so on (ok?!?)
now,
1. area code used in the school.txt must be defined in the area.txt
(Primary key in area => area_code defined in area.txt
& Foreign key on school => area_code defined in...
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by: rbarber |
last post by:
I have to synchronize 2 databases hourly but am having difficulty maintaining foreign key relations. These tables use auto-increment columns as primary keys, with child records in other tables related with foreign keys. I can't change the way the local software uses primary or foreign keys as it is hardcoded in the local app. (microsoft retail management system)..(however the web-remote app is easily customized). I am using CDB synchronizer to...
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by: apax999 |
last post by:
Kinda new to SQL, using SQL Server 2005.
I have some foreign keys in a couple of tables. I need to drop these
tables, but can't since I'll get the error:
Msg 3726,
Level 16, State 1, Line 1
Could not drop object 'Client' because it is referenced by a FOREIGN
KEY constraint.
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by: H |
last post by:
I have a dataset with Customers, Orders, and Items tables.
It has datarelations set between Customers-Orders and Orders-Items
It has foreignkeyconstraints with update/delete rules set to cascade
for Orders & Items.
The dataset is filled with Customers and their related Orders and
their related Items.
What is the most efficient way to create a second dataset that is a
subset of the main dataset, but only has data for Customer_id = "1"
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by: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look !
Part I. Meaning of...
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by: Hystou |
last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it.
First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
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by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it.
Here is my compilation command:
g++-12 -std=c++20 -Wnarrowing bit_field.cpp
Here is the code in...
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by: jinu1996 |
last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth.
The Art of Business Website Design
Your website is...
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by: tracyyun |
last post by:
Dear forum friends,
With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
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by: isladogs |
last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM).
In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules.
He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms.
Adolph will...
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by: conductexam |
last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one.
At the time of converting from word file to html my equations which are in the word document file was convert into image.
Globals.ThisAddIn.Application.ActiveDocument.Select();...
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by: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
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by: 6302768590 |
last post by:
Hai team
i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
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