Question

Im runing mySQL in a server where i need to drop tons of databases (after some testing with the server). All databases that i need to drop have the same prefix ‘Whatever_’.

After the prefix, the names are random. So you have your Whatever_something, Whatever_232, Whatever_blabla, …. , Whatever_imthelast.

I will be doing this job quite some times so i was wondering what would be the best way to do this?

EDIT: I can use any kind of language or plug in for mysql… so we CAN do this in some ways. Right now, i asked the guy that is generating the databases to give me a .txt with each name in a line… so im coding a quick php that will take a file and delete all the databases in it, later i will try the % answer(if it works, it takes the correct answer for sure its the easier way). Anyway i would like to do this the easier way coz i wont be able to support this code(other guys will and you know… )

edit 2: The use of a wildcard didnt work: #1008 – Can’t drop database ‘whatever_%’; database doesn’t exist

Answer 1

The basic idea is to run ‘show tables’ in your database, and use the results from that to select the tables you want. I don’t think MySQL lets you do anything with the resultset from ‘show tables’, but I’m probably wrong.

Here’s a quick-and-dirty solution using the shell:

mysql -u your_user -D your_database_name -e 'show tables' -s |    egrep '^Whatever_' |    xargs -I '@@' echo mysql -u your_user -D your_database_name -e 'DROP TABLE @@' 

That will print out all the shell commands to drop the tables beginning with ‘Whatever_’. If you want it to actually execute those commands, remove the word ‘echo’.

EDIT: I forgot to explain the above! I don’t know how familiar you are with shell scripting, but here goes:

mysql -u your_user -D your_database_name -e 'show tables' -s 

prints out a list of all your tables, with the header ‘Tables_in_your_database_name’. The output from that is piped (the | symbol means ‘piped’, as in passed-on) through the next command:

egrep '^Whatever_' 

searches for any lines that begin (that ^ symbols means ‘beings with’) the word ‘Whatever_’ and only prints those. Finally, we pipe that list of ‘Whatever_*’ tables through the command:

xargs -I '@@' echo mysql -u your_user -D your_database_name -e 'DROP TABLE @@' 

which takes each line in the list of table names, and inserts it instead of the ‘@@’ in the command

echo mysql -u your_user -D your_database_name -e 'DROP TABLE @@' 

So if you had a bunch of tables named ‘Whatever_1’, ‘Whatever_2’, ‘Whatever_3’, the generated commands would be:

echo mysql -u your_user -D your_database_name -e 'DROP TABLE Whatever_1' echo mysql -u your_user -D your_database_name -e 'DROP TABLE Whatever_2' echo mysql -u your_user -D your_database_name -e 'DROP TABLE Whatever_3' 

Which would output the following:

mysql -u your_user -D your_database_name -e 'DROP TABLE Whatever_1' mysql -u your_user -D your_database_name -e 'DROP TABLE Whatever_2' mysql -u your_user -D your_database_name -e 'DROP TABLE Whatever_3' 

I hope that was enough detail, and that I’m not just beating anyone over the head with too much information. Good luck, and be careful when using the ‘DROP TABLE’ command!