Select query on collection(table) in MongoDB
DOCUMENTS(ROWS)
Documents(rows) associate keys with values
{ field:value }
COLLECTION
A collection(table) is a group of related documents(rows) that have a set of shared common indexes.
Select statement
Select query for MongoDB to check all rows in collection(table in RDBMS).
db.employee.find() -- select * from employees;
Check column value like Select Statement
Example 1: Select name from employees;
db.employees.find({},{name:1}) -- sec
{ "_id" : ObjectId("540ebf2ffbf4b1a1447addec"), "name" : "abc123" }
{ "_id" : ObjectId("540ebf3ffbf4b1a1447added"), "name" : "qwe" }
{ "_id" : ObjectId("540ebf47fbf4b1a1447addee"), "name" : "zxc" }
{ "_id" : ObjectId("540ebf52fbf4b1a1447addef"), "name" : "asd" }
{ "_id" : ObjectId("540ebf5ffbf4b1a1447addf0"), "name" : "kkk" }
Example 2: select age from employees;
db.employees.find({},{age:1})
{ "_id" : ObjectId("540ebf2ffbf4b1a1447addec"), "age" : 55 }
{ "_id" : ObjectId("540ebf3ffbf4b1a1447added"), "age" : 20 }
{ "_id" : ObjectId("540ebf47fbf4b1a1447addee"), "age" : 25 }
{ "_id" : ObjectId("540ebf52fbf4b1a1447addef"), "age" : 35 }
{ "_id" : ObjectId("540ebf5ffbf4b1a1447addf0"), "age" : 23 }
Example 3: select name,status from employees
you can also use alternative method to disable age column 0
db.employees.find({},{age:0,_id:0})
{ "name" : "abc123", "status" : "A" }
{ "name" : "qwe", "status" : "A" }
{ "name" : "zxc", "status" : "A" }
{ "name" : "asd", "status" : "A" }
{ "name" : "kkk", "status" : "N" }
Example 4: If you do age:1 enable age
db.employees.find({},{age:1,_id:0})
{ "age" : 55 }
{ "age" : 20 }
{ "age" : 25 }
{ "age" : 35 }
{ "age" : 23 }
