Solved

Cardinality;PRIMARY Index;Indexes

Posted on 2006-07-19
3
896 Views
Last Modified: 2008-02-26
Can someone please explain what these terms mean/do?

Cardinality;PRIMARY Index;Indexes

I've seen them in phpmyadmin and are wondering what they are used for.
0
Comment
Question by:mnb93
  • 2
3 Comments
 
LVL 142

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 500 total points
ID: 17136887
Cardinality:
  means how many different values you have for 1 column. for a primary key or unique constraints , it must be 1
 

primary key:
  is a constraint enforcing you have each value only once in the table. trying to update or insert duplicate values will be rejected

indexes:
  like in books, a index is to find information quicker.
0
 
LVL 5

Author Comment

by:mnb93
ID: 17136927
if I set something to an index that does what? (one hand typing atm ,soory.)
0
 
LVL 142

Assisted Solution

by:Guy Hengel [angelIII / a3]
Guy Hengel [angelIII / a3] earned 500 total points
ID: 17137097
an index is a additional structure besides the table, kept up-to-date automatically, that helps WHERE clause to be fast.

like Persons table : PersonID, PersonName

if you don't put a index on PersonID, getting a single row can take more and more time, the larger the table.
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A lot of articles have been written on splitting mysqldump and grabbing the required tables. A long while back, when Shlomi (http://code.openark.org/blog/mysql/on-restoring-a-single-table-from-mysqldump) had suggested a “sed” way, I actually shell …
I use MySQL for many of my development projects in a Windows environment. To manage my databases (and perform queries) for years I used a tool called MySQL administrator.  This tool has since been replaced by MySQL Workbench. So I decided to m…
Migrating to Microsoft Office 365 is becoming increasingly popular for organizations both large and small. If you have made the leap to Microsoft’s cloud platform, you know that you will need to create a corporate email signature for your Office 365…
Many functions in Excel can make decisions. The most simple of these is the IF function: it returns a value depending on whether a condition you describe is true or false. Once you get the hang of using the IF function, you will find it easier to us…

895 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

13 Experts available now in Live!

Get 1:1 Help Now