Use of where condition in MongoDB

Example of using select(find) query with where condition in MongoDB.

Check the complete table detail as follows

db.employees.find( {},{_id:0})
{ "name" : "abc123", "age" : 55, "status" : "A" }
{ "name" : "qwe", "age" : 20, "status" : "A" }
{ "name" : "zxc", "age" : 25, "status" : "A" }
{ "name" : "asd", "age" : 35, "status" : "A" }
{ "name" : "kkk", "age" : 23, "status" : "N" }

Use of where clause with EQUAL operator in MongoDB

---In RDBMS example
select * from employees where status = 'A';

–In MongoDB
db.employees.find( {status: “A”} )

db.employees.find( {status:”A”},{_id:0})
Output:
{ “name” : “abc123”, “age” : 55, “status” : “A” }
{ “name” : “qwe”, “age” : 20, “status” : “A” }
{ “name” : “zxc”, “age” : 25, “status” : “A” }
{ “name” : “asd”, “age” : 35, “status” : “A” }

Use of IN-EQUAL operator in Where Clause

-- In RDBMS
select * from employees where status != 'A';

–In MongoDB
db.employees.find( { status: { $ne: “A” } } )

db.employees.find( { status: { $ne: “A” } }, {_id:0})
Output:
{ “name” : “kkk”, “age” : 23, “status” : “N” }

Use of greater then operator in where clause

-- In RDBMS
SELECT * FROM employees WHERE age >= 25

–In MongoDB
db.employees.find(  { status: “A”,age:{$gte:25} } )

db.employees.find(  { status: “A”,age:{$gte:35} }, {_id:0})
OUTPUT:
{ “name” : “abc123”, “age” : 55, “status” : “A” }
{ “name” : “asd”, “age” : 35, “status” : “A” }