Syntax examples

MongoDB Syntax Example

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MongoDB Update() Method

The update() method updates the values in the existing document. Syntax The basic syntax of update() method is as follows − >db.getCollection(COLLECTION_NAME).update(SELECTION_CRITERIA, UPDATED_DATA)
Assume the collection has the following data.
{ "_id" : ObjectId(5), "title":"MongoDB OV"}
{ "_id" : ObjectId(6), "title":"NoSQL OV"}
{ "_id" : ObjectId(7), "title":"AOQ OV"}
The following example will set the new title 'MongoDB Tut' of the documents whose title is 'MongoDB OV'.
>db.getCollection(COLLECTION_NAME).update({'title':'MongoDB OV'},{$set:{'title':'MongoDB Tut'}})
{ "_id" : ObjectId(5), "title":"MongoDB Tut"}
{ "_id" : ObjectId(6), "title":"NoSQL OV"}
{ "_id" : ObjectId(7), "title":"AOQ OV"}

By default, MongoDB will update only a single document. To update multiple documents, you need to set a parameter 'multi' to true.
>db.getCollection(COLLECTION_NAME).update({'title':'MongoDB OV'}, {$set:{'title':'MongoDB Tut'}},{multi:true})

Code on a screen

RDBMS Where Clause Equivalents in MongoDB


Operation Syntax Example RDBMS Equivalent
Equality {<key>:<value>} db.getCollection(COLLECTION_NAME).find({"by": AOQ})

db.getCollection(COLLECTION_NAME).find({"by": /AOQ/})
where 'by' = 'AOQ'

where 'by' like '%AOQ%'
Less Than {<key>:{$lt:<value>}} db.getCollection(COLLECTION_NAME).find({"likes":{$lt:10}}) where 'likes' < 10
Less Than or Equal {<key>:{$lte:<value>}} db.getCollection(COLLECTION_NAME).find({"likes":{$lte:10}}) where 'likes' <= 10
Greater Than {<key>:{$gt:<value>}} db.getCollection(COLLECTION_NAME).find({"likes":{$gt:10}}) where 'likes' > 10
Greater Than or Equal {<key>:{$gte:<value>}} db.getCollection(COLLECTION_NAME).find({"likes":{$gte:10}}) where 'likes' >= 10
Not Equal {<key>:{$ne:<value>}} db.getCollection(COLLECTION_NAME).find({"likes":{$ne:10}}) where 'likes' != 10
Code on a screen

RDBMS Where Clause Equivalents in MongoDB


Operation Syntax Example
AND db.getCollection(COLLECTION_NAME).find( { $or: [ {key1: value1}, {key2:value2} ] } ) db.getCollection(COLLECTION_NAME).find( { $and: [ {key1: value1}, {key2:value2} ] } )
OR db.COLLECTION_NAME.find( { $or: [ {key1: value1}, {key2:value2} ] } ) db.getCollection(COLLECTION_NAME).find( { $or: [ {key1: value1}, {key2:value2} ] } )
AND and OR simultaneously db.getCollection(COLLECTION_NAME).find({"key7": {$gt:Value7a}, $or: [{"key4": "value4"}, {"key2": "value2"}]})
{ "key1": Value1, "key2": "Value2", "key3": "Value3", "key4": "Value4", "key5": "Value5", "key6": ["Value6a", "Value6b", "Value6c"], "key7": "Value7b" }
db.getCollection(COLLECTION_NAME).find({"likes": {$gt:10}, $or: [{"by": "AOQ"}, {"title": "MongoDB OV"}]})
{ "_id": ObjectId(c), "title": "MongoDB OV", "description": "MongoDB descr", "by": "AOQ", "url": "", "tags": ["MongoDB", "DB", "NoSQL"], "likes": "500" }