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show dbs
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To see the list of databases in the system
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use dbsname
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Switched to db dbsname
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db.getName()
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To find out the currently selected database
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show collections
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To see the collections in a databases
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db.dbname.insert({colomname:"data", colomname:data})
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Save some data in the database
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db.dbname.insert({columnname:'stringdata', columnname:intdata})
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To create documents in a collection
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db.comedy.find()
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To read data from a collection
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db.collection.find({ "field" : { $gt: value } } )
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greater than : field > value
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db.collection.find({ "field" : { $lt: value } } )
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less than : field < value
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db.collection.find({ "field" : { $gte: value } } )
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greater than or equal to : field >= value
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db.collection.find({ "field" : { $lte: value } } )
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less than or equal to : field <= value
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db.comedy.find({year: { $gt: 2007, $lt: 2011} } )
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You can also combine these operators to specify ranges
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db.comedy.find({year:2012})
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And how do we do an 'equal to' query? Just match the value for the queried key
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db.comedy.find({year:{'$lt':2012}}, {name:true})
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What if you want to get only some fields in the result?
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db.comedy.find({year:{'$lt':2012}}, {name:false})
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What if you want to get all, except some fields in the result?
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db.comedy.find({year: {$ne: 2011}})
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Use $ne for "not equals".
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db.comedy.find({year: {$in: [2010,2011,2012]}})
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The $in operator is analogous to the SQL IN modifier, allowing you to specify an array of possible matches.
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db.comedy.find({year: {$nin: [2010,2011,2012]}})
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The $nin operator is similar to $in except that it selects objects for which the specified field does not have any value in the specified array
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db.comedy.find({year: {$nor: [2010,2011,2012]}})
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The $nor operator lets you use a boolean or expression to do queries. You give $nor a list of expressions, none of which can satisfy the query.
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db.comedy.find({$or: [{year: 2012}, {name: 'The hangover'}]})
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The $or operator lets you use boolean or in a query. You give $or an array of expressions, any of which can satisfy the query.
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db.comedy.find({$and:[{year: {$gt: 2010}}, {year:{$lt: 2012}}]})
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The $and operator lets you use boolean and in a query. You give $and an array of expressions, all of which must match to satisfy the query
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db.comedy.update({name:"Ted"}, {'$set':{director:'Seth MacFarlane', cast:['Mark Wahlberg', 'Mila Kunis', 'Matt Walsh', 'Jessica Barth', 'Aedin Mincks']}})
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update
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db.comedy.update({name:"Ted 2"}, {'$set':{year: 2015}}, {upsert: true})
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By specifying upsert: true, applications can indicate, in a single operation, that if no matching documents are found for the update, an insert should be performed.
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db.comedy.update({year:2012}, {'$set':{rating: 4}}, {multi: true})
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owever, with the multi option, update() can update all documents in a collection that match a query.
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db.comedy.update({name:"Ted"}, {'$push':{cast:'Joel McHale'}})
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Now how do you update a value which is an array?
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db.comedy.update({name:"Ted"}, {'$pull':{cast:'Giovanni Ribisi'}})
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If we need to remove something from the cast array. We do it this way:
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db.comedy.update({name:"Ted"}, {'$pop':{cast:-1}})
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We can also use $pop to remove the first element
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db.comedy.update({name:"Ted"}, {'$pop':{cast:1}})
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We can also use $pop to remove the last element
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db.articles.find({'meta.author':'Chad Muska'})
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To search an object inside an object, just use the regular JavaScript dot notation of the target object as the key AND quote it.
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db.articles.find({'meta.tags':'mongolia'})
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You need to query an array? No problem
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db.articles.find({'comments.by':'Steve'})
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When the key is an array, the database looks for the object right in the array. You need to look for an object inside an array?
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db.articles.find( { comments : { $size: 2 } } )
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The $size operator matches any array with the specified number of elements.
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db.comedy.find({name:{$regex: /bill|ted/i}})
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We can even use regular expressions in our queries
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db.comedy.find({name: /The hangover.*/i } );
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We can even use regular expressions in our queries
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db.comedy.find({name: {$regex: 'The hangover.*', $options: 'i'}});
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We can even use regular expressions in our queries
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db.comedy.find({name: {$regex: /The hangover.*/i, $nin: ['The Hangover Part II']}});
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If you wish to specify both a regex and another operator for the same field, you need to use the $regex clause.
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db.comedy.find({name: {$not: /The hangover.*/i}});
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The $not meta operator can be used to negate the check performed by a standard operator. For example:
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db.comedy.find('this.year > 2009 && this.name !== "Ted"')
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MongoDB queries support JavaScript expressions!
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db.comedy.find({$where: 'this.year > 2011'})
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MongoDB has another operator called $where using which you can perform SQL's WHERE-like operations.
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db.comedy.count()
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This will return the total number of documents in the collection named comedy
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db.comedy.count({year:{$gt:2009}})
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This will return the total number of documents in the collection named comedy with the value of year more than 2009:
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db.comedy.find().limit(2)
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To limit the collection to just two:
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db.comedy.findOne()
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Similar to using find().limit(1), there is a function called findOne(), which will get you only one document in the result.
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db.comedy.find().skip(1).limit(2)
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The skip() expression allows one to specify at which object the database should begin returning results.
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db.articles.find ({'meta.tags': {$all: ['mongodb', 'mongo']}});
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The $all operator is similar to $in, but instead of matching any value in the specified array all values in the array must be matched.
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db.articles.find ({title: {$exists : true}});
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Check for existence (or lack thereof) of a field.
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db. articles.find().sort({title : -1})
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sort() is analogous to the ORDER BY statement in SQL - it requests that items be returned in a particular order. We pass sort() a key pattern which indicates the desired order for the result.
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db.comedy.update({name:'Ted'}, {$unset:{cast:1}})
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How do you delete a field from a document?
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db.comedy.update({$unset:{cast:1}}, false, true)
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In case you want to delete a field from all the documents of a collection:
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db.comedy.remove({name:'Ted'})
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How do you delete a document from a collection?
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db.comedy.remove({})
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How do you empty a collection of its documents?
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db.comedy.drop()
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How do you delete / drop a collection?
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use movies; db.dropDatabase()
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To delete a database select the database and call the db.dropDatabase() on it:
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