Mongodb – Delete everything in a MongoDB database

mongodb

I'm doing development on MongoDB. For totally non-evil purposes, I sometimes want to blow away everything in a database—that is, to delete every single collection, and whatever else might be lying around, and start from scratch. Is there a single line of code that will let me do this? Bonus points for giving both a MongoDB console method and a MongoDB Ruby driver method.

Best Answer

In the mongo shell:

use [database];
db.dropDatabase();

And to remove the users:

db.dropAllUsers();

Related Solutions

Sql – How to query MongoDB with “like”

That would have to be:

db.users.find({"name": /.*m.*/})

Or, similar:

db.users.find({"name": /m/})

You're looking for something that contains "m" somewhere (SQL's '%' operator is equivalent to regular expressions' '.*'), not something that has "m" anchored to the beginning of the string.

Note: MongoDB uses regular expressions which are more powerful than "LIKE" in SQL. With regular expressions you can create any pattern that you imagine.

For more information on regular expressions, refer to Regular expressions (MDN).

Mongodb – How to get the last N records in mongodb

If I understand your question, you need to sort in ascending order.

Assuming you have some id or date field called "x" you would do ...

.sort()

db.foo.find().sort({x:1});

The 1 will sort ascending (oldest to newest) and -1 will sort descending (newest to oldest.)

If you use the auto created _id field it has a date embedded in it ... so you can use that to order by ...

db.foo.find().sort({_id:1});

That will return back all your documents sorted from oldest to newest.

Natural Order

You can also use a Natural Order mentioned above ...

db.foo.find().sort({$natural:1});

Again, using 1 or -1 depending on the order you want.

Use .limit()

Lastly, it's good practice to add a limit when doing this sort of wide open query so you could do either ...

db.foo.find().sort({_id:1}).limit(50);

db.foo.find().sort({$natural:1}).limit(50);