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by: Westcoast Sheri |
last post by:
Which will be a faster lookup of an item by, "color" in the following
mySQL tables: "unique key," "primary key," or just plain "key"??
CREATE TABLE myTable (
number int(11) NOT NULL default '0',
description varchar(50) NOT NULL default '',
color varchar(30) NOT NULL default '',
price decimal(3,2) NOT NULL default '0.00',
UNIQUE KEY (color)
);
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by: KULJEET |
last post by:
foreign key also refer to unique constraint.
(GREAT...)
1.then table that containt unique constraint act as master table?????
2.IS unique constraint will replace with primary key??
3.Is unique constraint gives all fuctionality as primary key constraint???
thanks
kuljeet pal singh
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by: Jason Madison |
last post by:
We sometimes get very large databases that we want to cut down to use for
testing.
The information is all related to a central accounts table.
The way I thought of doing this is to grab all the foreign constraints and
turn them into cascade delete constraints, then delete as many accounts as I
want.
After this I will restore the constraints back to their original state.
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by: Tibor |
last post by:
I am using PostgreSQL 7.4.1 (only through psql)
I know, that the command
ALTER TABLE OFFICES
DROP PRIMARY KEY (CITY);
and its foreign key equivalent:
ALTER TABLE SALESREPS
DROP CONSTRAINT
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by: Dennis Gearon |
last post by:
Given:
CREATE TABLE Usrs(
usr_id SERIAL NOT NULL PRIMARY KEY,
usr VARCHAR(64) NOT NULL UNIQUE
);
CREATE TABLE Emails(
email_id SERIAL NOT NULL PRIMARY KEY,
email VARCHAR(128) NOT NULL UNIQUE
);
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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: Laurence |
last post by:
Hi there,
How to differentiate between unique constraint and unique index? These
are very similar but I cannot differentiate them?
Could someone give me a hand?
Thanks in advance
|
by: Alvin SIU |
last post by:
Hi all,
I have a table in Db2 v8 like this:
Team Name Role
------ -------- ---------------------
A Superman Leader
A Batman Member
A WonderWoman Member
B Alvin Leader
|
by: rorajoey |
last post by:
Violation of UNIQUE KEY constraint 'IX_surveyQuestions'. Cannot insert duplicate key in object 'dbo.surveyQuestions'.
This might seem like a simple matter of trying to insert a row with ID=20 when there's already one with that ID, but the problem is a bit more complicated. The table is supposed to auto-increment the value for the primary key when a new record is inserted. But no matter what I do, I can't seem to insert more than one record...
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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: 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...
|
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...
|
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...
|
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();...
|
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: muto222 |
last post by:
How can i add a mobile payment intergratation into php mysql website.
|
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by: bsmnconsultancy |
last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...
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