This is a small tutorial to learn the basics of
MongoDB. The market for nosql is booming a lot!
Its always good to have a basic idea about
various nosql databases.
Installation with macOS:
- Try to install mongoDB
through brew (software package management system that
simplifies the installation of software on Apple MacOS)
- Go to https://brew.sh/ , copy
paste the Terminal prompt command and run it on the mac terminal.
- Run command: "brew install
mongodb" on your terminal.
- Make the data directory
"mkdir -p /data/db"
- Change the Owner "sudo chown
nelson /data/db"
- To see the databases created, type
the command "show dbs"
- In order to create a new db and/or to switch to another db, type in the terminal "use test_1" (here while typing this for the first time, the 'test_1' db is created as well as it will switch the db to 'test_1')
Now these are few basic operations:
1. Show the
document with db.test_1.find()
2. Update the
database to allow a list of references
nelsonDB.references = [ ]
db.test_1.update({"name" :
"Nelson"}, nelsonDB)
db.test_1.find()
// Will show the updated document
3. Show the
document with db.test_1.find()
4. Update the
database to allow a list of references
nelsonDB.references = [ ]
db.test_1.update({"name"
: "Nelson"}, nelsonDB)
db.test_1.find() // Will show the updated document
5. Use remove to delete the documents or with a parameter to delete just the one that
matches
db.test_1.remove({"name"
: "Nelson"})
db.test_1.find() // Will not show any result
6. Data Types
a. null : {"name"
: null}
b. boolean :
{"currentEmp" : true}
c. number : (64 bit float)
: {"height" : 6.25}
1.
4 byte Int : {"bigint" : 92949455}
2.
8 byte Long : {"bigLong" : 78443435227370955145644}
d. string :
{"address" : "N Avenue"}
e. Array containing multiple datatypes : array : {"grades" : ["a",
"b", "c", "d"]}
f. Date object :
{"hiredate" : new Date()}
g. Regular expression :
{"addressregex" : /^[A-Za-z0-9\.\' \-]{4,33}$/}
h. Embedded document :
{"info" : {"name" : "Baker Smith"}}
i. Object id (Unique for
every document) : 12 Byte ID for documents
j. Randomdata =
{"name" : null, "over20" : true, "height" : 6.25,
"bigint" : 92949455, "bigLong" : 78443435227370955145644,
"address" :
"N Avenue", "grades" : ["a", "b",
"c", "d"],
"hiredate" : new
Date(), "streetregex" : '/^[A-Za-z0-9\.\' \-]{5,30}$/',
"info" :
{"name" : "Baker Smith"}}
More about MongoDB
db.createUser ({
user: "Nelson",
pwd: "1234"
roles:
["readWrite”""dbAdmin"]
});
Create a User without Roles:
db.createUser ({
user: "Nelson",
pwd: "1234",
roles: []
});
Note*: If you type pass instead of pwd, it will throw the following error:
Error: couldn't add user: "pass" is not a valid argument to createUser
Collections are very similar to tables in database:
Create a collection:
db.createCollection('customers');
show collections
And insert few values:
db.customers.insert({"firstName":"John", "lastName":"Baker"})
db.customers.find()
If we need to add multiple row, use array
db.customers.insert([{"firstName":"Sarah", "lastName":"Anderson"},{"firstName":"Steve", "lastName":"Joseph",gender:"Male"}])
Output:
db.customers.find().pretty()
{
"_id"
: ObjectId("5a668d7608220527b462d543"),
"firstName"
: "John",
"lastName"
: "Baker"
}
{
"_id"
: ObjectId("5a668ebc08220527b462d544"),
"firstName"
: "Sarah",
"lastName"
: "Anderson"
}
{
"_id"
: ObjectId("5a668ebc08220527b462d545"),
"firstName"
: "Steve",
"lastName"
: "Joseph",
"gender" : "Male"
}
Note*: Here we can see that we can add one more field called "gender" into the document.
Now to update it always try to use the objectId instead of any
first_name as reference. Just for understanding purpose I have taken first_name
as a reference.
db.customers.update({"firstName":"Steve"}, {"firstName":"Steve", "lastName":"Joseph",gender:"Female"})
Note*: If we just use db.customers.insert({"firstName":"Steve"}, {gender:"Female"})
, it will replace the whole thing with just {gender:"Female"}
SET:
There is a way where this situation can be avoided, that is by
using SET
db.customers.update({"firstName":"Steve"}, {$set:{gender:"Female"}})
We can update a new field into it:
db.customers.update({"firstName":"Steve"}, {$set:{age:49}})
Increment age by 1:
db.customers.update({"firstName":"Steve"}, {$inc:{age:1}})
{
"_id" : ObjectId("5a668d7608220527b462d543"),
"firstName" : "John",
"lastName" : "Baker"
}
{
"_id" : ObjectId("5a668ebc08220527b462d544"),
"firstName" : "Sarah",
"lastName" : "Anderson"
}
{
"_id" : ObjectId("5a668ebc08220527b462d545"),
"firstName" : "Steve",
"lastName" : "Joseph",
"gender" : "Male",
"age":50
}
UNSET:
db.customers.update({"firstName":"Steve"}, {$unset:{age:1}})UNSET:
Age will be deleted from the document.
UPSERT:
If the item is not found during the update then by using UPSERT it will add the items if matching items is not available.
db.customers.update({"firstName":"Job"}, {"firstName":"Job", "lastName":"Martin"},{upsert:true});
After executing this a new document will be added.
RENAME:
db.customers.update({"firstName":"Steve"}, {$rename:{gender:"sex"}})
output:
{
"_id" : ObjectId("5a668d7608220527b462d543"),
"firstName" : "John",
"lastName" : "Baker"
}
{
"_id" : ObjectId("5a668ebc08220527b462d544"),
"firstName" : "Sarah",
"lastName" : "Anderson"
}
{
"_id" : ObjectId("5a668ebc08220527b462d545"),
"firstName" : "Steve",
"lastName" : "Joseph",
"sex" : "Female"
}
{
"_id" : ObjectId("5a668f1108220527b462d547"),
"firstName" : "Steve",
"lastName" : "Joseph",
"gender" : "Male"
}
{ "_id" : ObjectId("5a66911708220527b462d548"), "firstName" : "Steve" }
{
"_id" : ObjectId("5a66b4b404b58ba782f4043a"),
"firstName" : "Job",
"lastName" : "Martin"
}
REMOVE:
To remove the document
db.customers.remove({"firstName":"Steve"});
Note*: If the above statement is executed, all the document related to firstName = 'Steve' will be deleted.
So use justOne
db.customers.remove({"firstName":"Steve"},{justOne:true});
This is a kind of safety option which only deletes the first document.
QUERYING the Document:
db.customers.find({firstName:"Sarah"})
OR db.customers.find({$or: [{"firstName":"Steve"},{"firstName":"John"}]});
Greater Than / Less Than
db.customers.find({"age": [{lt:60}]}); // replace lt with gt for finding greater than.
also,
lte - less than or equal to
gte - greater than or equal to
Insert Object
db.customers.update({"firstName":"TinTin"}, {"address":{"street":"S Avenue","city":"tempe","state":"AZ"}},{upsert:true});
find value from inside the object:
db.customers.find({"address.city":"tempe"})
Sort
Sorting the component by lastName.
db.customers.find().sort({lastName:1});
Note*: Here 1 means it is sorted in the ascending order, -1 means descending order.
Count
db.customers.find().count()
specific search:
db.customers.find({gender:"male"}).count()
Limit
db.customers.find({gender:"Male"}).limit(4)
db.customers.find().limit(4).sort({lastName:1})
ForEach
db.customers.find().forEach(function(doc){print("Customer Name: "+doc.firstName)})
output:
Customer Name: John
Customer Name: Steve
Customer Name: Sarah
Customer Name: Steve
Customer Name: Steve
Customer Name: Job
Customer Name: Job
