Jump to content

Archived

This topic is now archived and is closed to further replies.

Neptunus Maris

index and unique

Recommended Posts

I have a general understanding of what the unique column of a table is...

I need to know the difference between Unique and Index fields.  and please define them, my book doesnt go in dept.


Thanks in advance

Neptune

Share this post


Link to post
Share on other sites
Exactly as it says on the tin. Values in a unique index cannot have duplicates. If the index comprises more than one column then the combination of values must be unique.

So if your current index values are , say
[pre]
blue |  1
blue |  2
red  |  1
red  |  3
[/pre]
you could add "blue, 3" but not another "blue, 2"

Share this post


Link to post
Share on other sites

×

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.