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