Delete everything in a MongoDB database
In the mongo shell: use [database]; db.dropDatabase(); And to remove the users: db.dropAllUsers();
mongodb
When to use MongoDB or other document oriented database systems? [closed]
In NoSQL: If Only It Was That Easy, the author writes about MongoDB: MongoDB is not a key/value store, it’s quite a bit more. It’s definitely not a RDBMS either. I haven’t used MongoDB in production, but I have used it a little building a test app and it is a very cool piece of … Read more
Find objects between two dates MongoDB
Querying for a Date Range (Specific Month or Day) in the MongoDB Cookbook has a very good explanation on the matter, but below is something I tried out myself and it seems to work. items.save({ name: “example”, created_at: ISODate(“2010-04-30T00:00:00.000Z”) }) items.find({ created_at: { $gte: ISODate(“2010-04-29T00:00:00.000Z”), $lt: ISODate(“2010-05-01T00:00:00.000Z”) } }) => { “_id” : ObjectId(“4c0791e2b9ec877893f3363b”), “name” … Read more
Mongod complains that there is no /data/db folder
You created the directory in the wrong place /data/db means that it’s directly under the “https://stackoverflow.com/” root directory, whereas you created ‘data/db’ (without the leading /) probably just inside another directory, such as the ‘/root’ homedirectory. You need to create this directory as root Either you need to use sudo , e.g. sudo mkdir -p … Read more
How do you rename a MongoDB database?
You could do this, if you’re using MongoDB < 4.2 (ref): db.copyDatabase(“db_to_rename”,”db_renamed”,”localhost”) use db_to_rename db.dropDatabase(); Editorial Note: this is the same approach used in the question itself but has proven useful to others regardless.
Pretty print in MongoDB shell as default
(note: this is answer to original version of the question, which did not have requirements for “default”) You can ask it to be pretty. db.collection.find().pretty()
How do I perform the SQL Join equivalent in MongoDB?
As of Mongo 3.2 the answers to this question are mostly no longer correct. The new $lookup operator added to the aggregation pipeline is essentially identical to a left outer join: https://docs.mongodb.org/master/reference/operator/aggregation/lookup/#pipe._S_lookup From the docs: { $lookup: { from: <collection to join>, localField: <field from the input documents>, foreignField: <field from the documents of the … Read more
How do you query for “is not null” in Mongo?
This will return all documents with a key called “IMAGE URL”, but they may still have a null value. db.mycollection.find({“IMAGE URL”:{$exists:true}}); This will return all documents with both a key called “IMAGE URL” and a non-null value. db.mycollection.find({“IMAGE URL”:{$ne:null}}); Also, according to the docs, $exists currently can’t use an index, but $ne can. Edit: Adding … Read more
MongoDB relationships: embed or reference?
This is more an art than a science. The Mongo Documentation on Schemas is a good reference, but here are some things to consider: Put as much in as possible The joy of a Document database is that it eliminates lots of Joins. Your first instinct should be to place as much in a single … Read more
Checking if a field contains a string
You can do it with the following code. db.users.findOne({“username” : {$regex : “son”}});