how many columns does a table support?

iongion

My questions is :

Is there a maximum number of columns in a table?

What is the normal , average number of columns in a table?

Is there an article on the web that tells how to design a database for performance and clarity ?

Thx.

dopey

Try searching google for 'database normalization' - that should return you some tutorials on how to structure your db.

Or see: http://www.phpbuilder.com/columns/barry20000731.php3

Re max num of columns - I believe the maximum row length is 65534 bytes

From mysql manual:

The maximum record length in bytes can be calculated as follows:
row length = 1
+ (sum of column lengths)
+ (number of NULL columns + 7)/8
+ (number of variable-length columns)

Cheers,
Andy

swoolf

iongion -

Check out this tutorial, also:

http://www.mysql.com/articles/ddws/index.html

It's quite good on covering the basics.

There is no "normal" amount of columns in a table - it depends on what you need to store. MySQL can support an amzing amount of information, so probably any table you create that has dozens or even hundreds of columns would function, though likely not very well.

Learn the basics of db design first and you'll see why it's better to use a series of smaller tables to break up larger one with indexes that related information to each other.

Steve

iongion

Thanks a lot , this helped me very much , thank you all!