If we want SQL like “Like” operator in Mongo DB for string matching. But in mongo DB there is no such “like” operator instead it has regular expression to achieve a similar feature.

db.users.insert({name: 'singh'})
db.users.insert({name: 'singhak'})
db.users.insert({name: 'aksingh'})

Case 1:

In MongoDB, you can also use regular expression objects (i.e. /pattern/) to specify regular expressions:

Syntax: { <field>: /pattern/<options> }

Example 1.

--SQL
SELECT * FROM users  WHERE name LIKE '%sin%'

--MongoDB
db.users.find({name: /sin/})

Example 2.

--SQL
SELECT * FROM users  WHERE name LIKE '%gh'

--MongoDB
db.users.find({name: /gh$/})

Example 3.

--SQL
SELECT * FROM users  WHERE name LIKE 'ak%'

--MongoDB
db.users.find({name: /^ak/})

If we want ignorecase we can use like this

db.users.find({name: /Sin/i})

Also Read : Start mongo DB as Service

Case 2.

we can use $regex operator, it provides regular expression capabilities for pattern matching strings in queries. MongoDB uses Perl compatible regular expressions (i.e. “PCRE” ) version 8.42 with UTF-8 support.

Examples

db.user.find( { name: { $regex: /ak$/ } } )

db.user.find( { name: { $regex: /^sin/ } } )

db.user.find( { name: { $regex: /Sin/i } } )

db.user.find( { name: { $regex: '.*IN.*', $options:'is' } } )

db.user.find( { name: { $regex: /^sin/ } } )

Reference : MongoDB Regex