question about show databases;

[John Salerno]

Hi everyone. I just installed MySQL on my home PC and I tested out the
show databases query, and it lists two:

information_sch ema
bbdatabank

The second one is one I created myself, but I don't understand what the
first one is. It is not listed in my 'data' folder, but mysql and test
*are*, yet they aren't listed when I type the show command. Why is that?
How can I get them listed so that I can use them, and what is the
information_sch ema?

Thanks!
John

[Gordon Burditt]

>Hi everyone. I just installed MySQL on my home PC and I tested out the

show databases query, and it lists two:

information_sc hema
bbdatabank

The second one is one I created myself, but I don't understand what the
first one is. It is not listed in my 'data' folder, but mysql and test
*are*, yet they aren't listed when I type the show command. Why is that?
Unless you have the "show databases" privilege, you can only see
databases you have some privileges on.
How can I get them listed so that I can use them, and what is the
information_sc hema?

Use a username and a password with privileges to use them (e.g. the
root account set up when you installed MySQL).

information_sch ema is a database giving information on the databases
and stuff in them. Another way of getting a list of databases is
"select schema_name from information_sch ema.schemata". It is
automatically generated from the databases, so if you create or
delete tables or columns in them, it's automatically up to date.
On the other hand, it tends to be a bit slow if you list a whole
table.

Some of the information in information_sch ema is sensitive to privileges.
You may not see the rows for things you don't have access to.

Gordon L. Burditt

[John Salerno]

Gordon Burditt wrote:

Use a username and a password with privileges to use them (e.g. the
root account set up when you installed MySQL).

information_sch ema is a database giving information on the databases
and stuff in them. Another way of getting a list of databases is
"select schema_name from information_sch ema.schemata". It is
automatically generated from the databases, so if you create or
delete tables or columns in them, it's automatically up to date.
On the other hand, it tends to be a bit slow if you list a whole
table.

Thank you! I realized that I wasn't seeing mysql or test because I
wasn't signed in as the root account. As for the other question, thanks
for explaining. I'll just leave it alone! :)

[Gordon Burditt]

>> information_sch ema is a database giving information on the databases

and stuff in them. Another way of getting a list of databases is
"select schema_name from information_sch ema.schemata". It is
automatically generated from the databases, so if you create or
delete tables or columns in them, it's automatically up to date.
On the other hand, it tends to be a bit slow if you list a whole
table.

Thank you! I realized that I wasn't seeing mysql or test because I
wasn't signed in as the root account. As for the other question, thanks
for explaining. I'll just leave it alone! :)

information_sch ema does have its uses. For example, it's easy to
list all the tables with a 'stamp' column in them. And information_sch ema
is a bit less MySQL-specific than various "SHOW" commands, and you
can put a WHERE clause on the queries.

It *is* a really good idea to leave information_sch ema alone when
using mysqldump or restoring the output of mysqldump.

Gordon L. Burditt