MongoDb cheatsheet.txt

Connect to MongoDb shell
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mongo "<server-address>/<database>" --username <username> --password <password>


MongoDb shell commands
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Show selected db
> db  

List databases
> show dbs                                

Select database  
> use <dbName>                            

List active databaae collectuons 
> show collections                        

CRUD operatins
db.<collection>.[find|insert|update|replace|delete](<selector>)

Execute js file (useful for importing data)
> run("<path-to-js>")                      


Selectors Examples
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db.<collectionName>.find( {filter} )                list all documents (rows) in collectionName
db.<collectionName>.find( { color:"red", length: 100 } )     

db.<collectionName>.find( {filter} , {projection})  Set propertes to be returned  (prop:boolean)
db.<collectionName>.find( { color:"red", length: 100 }, { color: true } )     

db.<collectionName>.find( {"tripduration": {$exists: true} } )  <---return only documnts that have te specified property defined


Nested ObJects (dot notation)
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db.<collectionName>.find( { "box.color":"red"} )     <--- quotes are needed for nested objects   

Arrays Manipulation
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db.<collectionName>.find( { "actors": ["Arnold"]} )  <--- get docs where single index array has Arnold
db.<collectionName>.find( { "actors": ["Arnold","Lina"]} ) <--- get docs where actors matches (strict)
db.<collectionName>.find( { "actors":"Arnold"} )  <--- get entries where actors contains Arnold
db.<collectionName>.find( { "actors.0":"Arnold"} )  <--- get entries where actors index 0 is Arnold
db.<collectionName>.find(  {countries: {$size:2}}  ) //  eturn all documents where the countrynarray has only 2 elements


db.<collectionName>.find(  {$or : [ {watlev:"always dry"}, {depth: 0}] }  ) //  watlev=="always dry" || depth==0

db.<collectionName>.find( {JSON_filters} ).count()     
db.<collectionName>.find( {JSON_filters} ).pretty()    

db.<collectionName>.insertOne({JSON})   Inserts the document defined using JSON

db.<collectionName>.insertMany([ {JSON} ,{JSON} ,...])  Inserts the documents defined using JSON Array
db.<collectionName>.insertMany([ {JSON} ,{JSON} ,...] , {ordered:true|false} ) 
    - ordered insertn(default) : stops inserting after an error has been found
    - unordered insert : keeps going even in¡f errors are encontuntered



db.<collectionName>.updateOne({JSON}, { $set:{ <field>:value } } )   Updates the first document that matcjes the selector
db.<collectionName>.updateMany({JSON}, { $set:{ <field>:value } } )   Updates all documents that match  the selector
db.<collectionName>.updateMany({JSON}, { $set:{ <field>:value } }, {upsert:true} )   if the document selected by the query does not exist create it

db.<collectionName>.updateOne({JSON}, { $inc:{ <field>: incrementValue } } )  Increments


db.<collectionName>.updateOne({JSON}, { $push: { <field>: value } } )            Push to array  
db.<collectionName>.updateOne( { _id: 1 }, { $push: { scores: 89 } } )
db.<collectionName>.updateOne( { _id: 1 }, { $push: { scores: { $each: [ 90, 92, 85 ] } } } )


db.<collectionName>.updateOne( { _id: 1 }, { $unset: { <field> : false } } )     delete a field

db.<collectionName>.replaceOne( { _id: 1 },  { document } )     replaces the document of the query


db.<collectionName>.deleteOne( { _id: 1 } )   
db.<collectionName>.deleteMany( { selector } )   






Compass:
filter
{genres: "Comedy"}          // returns all documents wich genere contains Comedy