I'm developing a website with six products. The DBMS is MySQL. I want
to design seven databases on one DBMS,namely, MySQL, one for each, and
the 7th database is a common database shared among the six
products.There is a problem, I often need cross-
database operations. I want to create some stored procedures/routines
and some of them need cross-database operations and I don't know how
to do it.It is MySQL. Is it a good idea to design only one database
(the parameter in mysql_select_db()) with many many tables? What are
the advantages and disadvantages?

For example, on the website of yahoo.com, there are so many web
products, Yahoo! answers is one of them. On the website of google.com,
there are so many products,say,Google Web search, Google shopping,
Google maps, gmail, etc. There is one website(one domain) with many
subdomains,say,google.com is a domain, and images.google.com is a
subdomain. One owner will own the entire website.

I was surprised the concept "database" in phpMyadmin is the same as
the concept "schema", which is the very parameter in mysql_select_db
(). So what do you mean by "database" or "schema"?

Phper schreef:
> I'm developing a website with six products. The DBMS is MySQL. I want
> to design seven databases on one DBMS,namely, MySQL, one for each, and
> the 7th database is a common database shared among the six
> products.There is a problem, I often need cross-
> database operations. I want to create some stored procedures/routines
> and some of them need cross-database operations and I don't know how
> to do it.It is MySQL. Is it a good idea to design only one database
> (the parameter in mysql_select_db()) with many many tables? What are
> the advantages and disadvantages?

If the products in the database are related, why not stuff them all into
one and the same database?
However, if there are six different costumers, you better use 6 databases.


>
> For example, on the website of yahoo.com, there are so many web
> products, Yahoo! answers is one of them. On the website of google.com,
> there are so many products,say,Google Web search, Google shopping,
> Google maps, gmail, etc. There is one website(one domain) with many
> subdomains,say,google.com is a domain, and images.google.com is a
> subdomain. One owner will own the entire website.

You can easily connect from the same PHP script to many different
databases, even different brands.
Simply make more connections.


>
> I was surprised the concept "database" in phpMyadmin is the same as
> the concept "schema", which is the very parameter in mysql_select_db
> (). So what do you mean by "database" or "schema"?

Database is the general word describing the whole thing.
A schema means (in Postgresql at least) the structure and relations
inside one database.
So you say: I use database MySQL, and this particular instance has its
schema defined here and here.
So the schema says how the tables are named, what colums they hold, what
relation certain columns have to other tables (foreign keys), etc, etc.
In casual writing they are interchangable.

Regards,
Erwin Moller

Phper wrote:
[..]
> For example, on the website of yahoo.com, there are so many web
> products, Yahoo! answers is one of them. On the website of google.com,
> there are so many products,say,Google Web search, Google shopping,
> Google maps, gmail, etc. There is one website(one domain) with many
> subdomains,say,google.com is a domain, and images.google.com is a
> subdomain. One owner will own the entire website.
>
> I was surprised the concept "database" in phpMyadmin is the same as
> the concept "schema", which is the very parameter in mysql_select_db
> (). So what do you mean by "database" or "schema"?

Database design is best asked in a database newsgroup - such as
comp.databases.mysql in your case. You'll find the database experts
there with better answers to your questions.

Erwin Moller wrote:
> Phper schreef:
>
> If the products in the database are related, why not stuff them all into
> one and the same database?
> However, if there are six different costumers, you better use 6 databases.
>>
> You can easily connect from the same PHP script to many different
> databases, even different brands.

Strictly, you don't make a new connection: Just use mysql_select_db

However cross database joins are not possible.

The Natural Philosopher wrote:
> Erwin Moller wrote:
>
> Strictly, you don't make a new connection: Just use mysql_select_db
>
> However cross database joins are not possible.

Incorrect.

Jerry Stuckle wrote:
> The Natural Philosopher wrote:
>
> Incorrect.
>
Example in Mysql.?

The Natural Philosopher schreef:
> Jerry Stuckle wrote:
> Example in Mysql.?

Go to google: type: cross database joins mysql
follow first link. ;-)

http://www.shawnhogan.com/2005/12/cr...ith-mysql.html

Regards,
Erwin Moller

The Natural Philosopher wrote:
> Jerry Stuckle wrote:
> Example in Mysql.?

It's off-topic in a PHP newsgroup. Learn to use Google - or read the doc.

On 1 May, 16:20, Phper <histeven> wrote:
[..]
> For example, on the website of yahoo.com, there are so many web
> products, Yahoo! answers is one of them. On the website of google.com,
> there are so many products,say,Google Web search, Google shopping,
> Google maps, gmail, etc. There is one website(one domain) with many
> subdomains,say,google.com is a domain, and images.google.com is a
> subdomain. One owner will own the entire website.
>
> I was surprised the concept "database" in phpMyadmin is the same as
> the concept "schema", which is the very parameter in mysql_select_db
> (). So what do you mean by "database" or "schema"?

This is rather off-topic here, and your terminology is very confusing
- based on the examples you provided you seem to be describing 6
services or applications - not products.

Without doing a lot of analysis work on your website (no, that was not
an invitation) its hard to say for sure, but splitting the
applications into dedicated databases may simplify a lot of the
management of the site - the key thing is to identify if you have any
joins across the applications and see how practical it would be to
eliminate them. Also read up on MySQL replication.

C.