05.Mongo DB - Query part 1 (Create,Insert,Update,Drop,Remove,Find,limit,skip,sortAND,OR,INDEX)

  

Project can be download from 

      https://github.com/LahiruPriyankara/SpringBootAppTwo-MongoDB

Commands which we use in mongoDB.

Create a database

use company  // create a database

If it is already exist provide it, otherwise create it.

View all databases

show dbs

Database එකක් අලුතෙන් create කර මෙම command එක run කලද එම අලුත් database එකට document එකක් add වන තුරු එම database එක පෙන්වන්නේ නැත.

Drop a data base

db.dropDatabase() //Dropping a current woking database

 

 Create a collection.

db.createCollection("branch")

db.branch.insert({"code":"001", "name":"branch one"})

// create a document. Inhere branch Collection also create and then document is created.

View Collections

show collections // show created collection

 

View Collection data

db.branch.find()

 

Drop a Collection

db.employee.drop() // remove collection

 

Adding Document.

මෙහෙදී Binary Jason Format හෙවත් BSON එක යොදා ගනු ලබයි.

Single record.

db.branch.insert({"code":"001", "name":"branch one"})

 

 Multiple record.

db.branch.insert(

[

{"bId":"001", "bLocation":"Colombo","bTP":"b0771234567"},

{"bId":"002", "bLocation":"Kandy","bTP":"b0771235567"},

{"bId":"003", "bLocation":"Galle","bTP":"b0771230000"}

]

)

අපි Database එකට  data insert කරන විට mongoDB වලින් ඒ ඒ record එකට default ම unique id එකක් generate කරගනු ලබයි.එම ID එක අපට provide කරනටද පුළුවන් වේ.

Finding data.

find() and fIndOne() සැලකිමේදී find() මගින් entire collection එකේම search කර අදාළ සියලුම document ලබා දෙන අතර, findOne() මගින් පලවෙනි එක හොයාගත්තම document එක return කිරීම කරයි.එම නිසා find() ට වඩා findOne() එක speed වේ.

db.employee.find()

db.employee.findOne()

db.employee.find({"code":"001"})

db.employee.findOne({"code":"001"})

// find one is more speed because it find 1st result and return it.Bu in find() it will find all the record in the entire collection.

db.employee.find({"salary":"23000"}) // equal

db.employee.find({"salary":{$ne :"23000"}}) // not equal

db.employee.find({"salary":{$gt :"23000"}}) // gt - breater than

db.employee.find({"salary":{$gte :"23000"}}) //gte - greater than or equal

db.employee.find({"salary":{$lt :"29000"}}) // lt - breater than

db.employee.find({"salary":{$lte :"29000"}}) //lte - greater than or equal

db.employee.find({"salary":{$in :[100,200]}}) //in- salary in

db.employee.find({"salary":{$nin :[100,200]}}) //nin- salary in

AND, OR conditions (SQL වලනම් && සහ ||).

//And

db.employee.find({"salary":"23000","age":45})

db.employee.find({"salary":{$gt :"20000"},"age":{$gt :35}})

db.employee.find({$and: [{"salary":"23000","age":45}]})

db.employee.find({$and: [{"salary":{$gt :"20000"},"age":{$gt :35}}]})

//Or

db.employee.find({$or : [{"salary":"23000","age":45}]})

db.employee.find({$or : [{"salary":{$gt :"20000"},"age":{$gt :35}}]})

//both

db.employee.find({"age":{$lt :55},$or : [{"code":"002","salary":{$gt :"20000"}}]})

Updating

// updating

db.employee.update({"_id" : ObjectId("5f5ca367ccb1774f207b1dd7")},{$set:{"salary" : "28000"}})

//age එක 50 ට අඩු පළමු document එක විතරක් update කරයි.

db.employee.update({"age":{$lt :50}},{$set:{"salary" : "25000"}})

// age එක 50 ට අඩු සියලුම document update කරයි.

db.employee.update({"age":{$lt :50}},{$set:{"salary" : "25000"}},{multi:true})

db.employee.save({ "_id" : ObjectId("5f5ca367ccb1774f207b1dd7"), "code" : "002", "addrss" : "Main Steet,Kandy 04", "salary" : "25000", "age" : 36.0})

save වලදී id = "5f5ca367ccb1774f207b1dd7" search කරන අතර එහෙම එකක් තියනවනම් new valuess වලින් old එක update කරන අතර එහෙම එකක් නැත්තන් new document එකක් create කරනු ලබයි.

Removing Elements.

//කිසිම augment එකක් pass නොකරන්නේ නම් employee collection එකේ ඇති සියලුම documents remove කරනු ලබයි.

db.employee.remove()

db.employee.remove({"_id" : ObjectId("5f5ca367ccb1774f207b1dd7")})

// remove all documents, which age is = 45

db.employee.remove({"age":45})

// even given condition find multiple documents, then delete one document only

db.employee.remove({"age":45},1)

limit, skip and sort

// employee collection එකෙන් document 2k පමණක් fetch කරන්න

db.employee.find({},{"age":1,"_id":0,"code":1, "addrss":1,"salary":1}).limit(2)

// employee collection එකෙන් document වල පළමු 2k අත්හැර ඉතුරු ටික පමණක් fetch කරන්න 

db.employee.find({},{"age":1,"_id":0,"code":1, "addrss":1,"salary":1}).skip(2)

db.employee.find({},{"age":1,"_id":0,"code":1, "addrss":1,"salary":1}).limit(2).skip(1)

// Both are same.පළමුවෙනි document එක අතහැර ඊලග document දෙක ගන්න

db.employee.find({},{"age":1,"_id":0,"code":1, "addrss":1,"salary":1}).skip(1).limit(2)

// get document according acceding order of salary.[23000,290000,33000]

db.employee.find({},{"age":1,"_id":0,"code":1, "addrss":1,"salary":1}).sort({"salary":1})

// get document according descending order of salary.[33000,290000,23000]

db.employee.find({},{"age":1,"_id":0,"code":1, "addrss":1,"salary":1}).sort({"salary":-1})

Indexing

Indexes are the special data structure that sores a small portion of data set to easy to pass way. Mongo database is really large, it can have millions of records. If we want to find one document among those it is very important to use indexing.

Adding large amount of document to test the indexing.

for(i = 5; i<1000000;i++){

db.employee.insert(

{"code":"003"+i, "addrss":"Main Steet,Galle "+i,"salary":"33000","age":55}

)

}

Create index

db.employee.createIndex({"salary":1})

 

Fetch document

db.employee.find({"salary":"23000"})

 

Drop Index

db.employee.dropIndex({"salary":1})