Simple Basic Commands For MongoDB

Simple Basic Commands For MongoDB

     1.  Create a database named “mydb”

      >  Use mydb

     2.  Show all databases

      >  Show dbs

    

     3.     Show currently selected database.

>  DB

     4.     Create a collection named “emp”.

>  db.createCollection(“emp”)

     5.     Show all collections of the selected database.

>  Show collections

6. Insert following documents in emp collection:

>  db.emp.insert(

[

{ empno : 1,ename : "Sachin",sal : 60000,desige : "Manager",dept : "Purchase" },

{ empno : 2,ename : "Kohali",sal : 50000,desige : "Manager",dept : "Sales" }])

Find()

1.     List all documents.

> db.emp.find()

2.     List all documents with formatted output.

> db.emp.find.pretty()

3.     List the document of an employee whose name is “Sachin”

> db.emp.find({ename:”Sachin”})

4.     List the documents of employee whose salary is less than 30000

 > db.emp.find({sal : {$lt : 30000}})

5.     List employees whose designation is manager and department is sales.

> db.emp.find( { desige : "Manager",dept : "Sales"})

6.     List employees whose salary is less than 50000 and designation is manager or department is admin.

> db.emp.find(

{sal : {$lt : 50000},

$or : [

{ desige : "Manager"},{dept : "Admin"}

]})

7.     Arrange the records by name in descending order.

> db.emp.find().sort({ename : -1})

8.     List first 3 documents of emp collection.

> db.emp.find().limit(3)

1.     Skip first 3 documents of emp collection.

> db.emp.find().skip(3)

2.     List 3^rd and 4^th documents of emp collection.

> db.emp.find().limit(2).skip(2)

3.     Count no. of employees.

> db.emp.find().count()

4.     List distinct designation.

> db.emp.distinct(“desige”)

Aggregate()

1.     Calculate annual salary of employees.

> db.emp.aggregate( [ {      $project:{_id:0,ename:1,sal:1,desige:1,dept:1,Annual_Salary:{$multiply:["$sal",12]}}}]).pretty()

2.     Display no. of employees designation wise.

>db.emp.aggregate( [ {  $group :  { _id:"$dept",Employees:{$sum:1}}}] )

3.     Display total salary of employees department wise.

>  db.emp.aggregate( [ {      $group:      { _id:"$dept",Tot_Sal:{$sum:"$sal"} }} ] )

4.     Display employee whose salary is highest.

> db.emp.aggregate( [ {  $sort:{sal: -1}}, {  $limit: 1} ] )

5.     List highest salary of the employee department wise.

> db.emp.aggregate( [ {  $group:{ _id : "$dept",Highest_Sal : {$max:"$sal"} } } ] )

6.     Calculate total salary of employees department wise and list whose total is greater than 70000.

> db.emp.aggregate( [ { $group: {_id:"$dept",total_sal:{$sum:"$sal"}}},{ $match: {total_sal:{$gt:70000}}}])

Index()

7.     Create index on empno field.

> db.emp.ensureIndex( { empno:1} )

8.     Check the statistics of the emp collection.

> db.emp.stats()

9.     Get the list of all indexes created on the emp collection.

> db.emp.getIndexes()

10.                        Use hint method.

> db.emp.find( { empno:3}).hint({empno:1})

11.                        Use explain method.

> db.emp.find( { empno:3} ).hint({ empno:1}).explain()

Update()

12.                        Increment salary by 2000 whose name is Sachin.

> db.emp.update({ ename:"Sachin"},{$inc:{sal:2000}})

13.                        Increment salary by 2000 of all the employees.

> db.emp.update({}, { $inc:{sal:2000}},{multi:true})

14.                        Update designation of Sachin with CEO.

>  db.emp.update({ename:"Sachin"},{$set:{desig:"CEO"}})

15.                        Update designation of Sachin with ‘MD’ and insert as new document.

> db.emp.update({ename:"Sachin"},{$set:{desig:"MD"}},{upsert:true})

16.                        Add a new field “remark” to document with name “dhoni” and set remark “head”

> db.emp.update({ename:"Dhoni"},{$set:{remaek:"head"}})

17.                        Remove the added new field.

> db.emp.update({ename:"Dhoni"},{$unset:{remaek:"head"}})

Save()

18.                        Replace the whole document whose _id is 1.

> db.emp.save( {_id: ObjectId("59860ee940b855fbf3566a20") , empno:1,ename:"Tendulkar",sal:"40000",desig:"Clerk",dept:"Admin"})

Regular Expression :

19.                        To find documents from the emp collection where the ename begins with “S”. (with and without regex)

> db.emp.find({ename:/^S/})

> db.emp.find({ename:{$regex:"^S"}})

20.                        To find documents from the emp collection where the ename ends with “n”. (with and without regex)

> db.emp.find({ename:/n$/})

> db.emp.find({ename:{$regex:"n$"}})

21.                        Modify above query with case insensitivity.

> db.emp.find({ename:/N$/i})

> db.emp.find({ename:{$regex:"n$",$options:"i"}})

22.                        To find documents from the emp collection where ename has an “a” in any position.

> db.emp.find({ename:/a/})

> db.emp.find({ename:{$regex:".*a.*"}})

Dealing with null values :

23.                        Update the document with null value in designation field where name is “Kohli”.

> db.emp.update( {ename:"Kohali"}, {$set:{desig:null}} )

24.                        To search for null values in designation field.

> db.emp.find( {desig:null})

25.                        To remove designation field having null values in emp collection where name is “Kohli”.

> db.emp.update( { ename:"Kohali"},{$unset:{desig:null}})

DAA : ALGORITHAM :