How to get the equivalent for SELECT column1, column2 FROM tbl in MongoDB Database?

In MongoDB, you can select specific fields (columns) from a collection using projection in the find() method. This is equivalent to the SQL SELECT column1, column2 FROM table statement.

Syntax

db.collectionName.find({}, {"field1": 1, "field2": 1})

Use 1 to include fields and 0 to exclude fields. The _id field is included by default unless explicitly excluded.

Sample Data

db.customers.insertMany([
    {"CustomerName": "John", "CustomerAge": 26, "CustomerCountryName": "US"},
    {"CustomerName": "David", "CustomerAge": 22, "CustomerCountryName": "AUS"},
    {"CustomerName": "Chris", "CustomerAge": 24, "CustomerCountryName": "UK"}
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("..."),
        ObjectId("..."),
        ObjectId("...")
    ]
}

Example 1: Select Specific Fields (Include _id)

db.customers.find({}, {"CustomerName": 1, "CustomerAge": 1});

{
    "_id": ObjectId("5c92c6205259fcd19549980a"),
    "CustomerName": "John",
    "CustomerAge": 26
}
{
    "_id": ObjectId("5c92c6305259fcd19549980b"),
    "CustomerName": "David",
    "CustomerAge": 22
}
{
    "_id": ObjectId("5c92c6415259fcd19549980c"),
    "CustomerName": "Chris",
    "CustomerAge": 24
}

Example 2: Select Fields Without _id

db.customers.find({}, {_id: 0, "CustomerName": 1, "CustomerAge": 1});

{"CustomerName": "John", "CustomerAge": 26}
{"CustomerName": "David", "CustomerAge": 22}
{"CustomerName": "Chris", "CustomerAge": 24}

Key Points

• Use 1 to include specific fields in the result
• Use 0 to exclude fields (commonly used for _id)
• The _id field is automatically included unless explicitly set to 0
• You cannot mix inclusion and exclusion operators except for _id

Conclusion

MongoDB's projection feature in find() provides the equivalent functionality to SQL's SELECT statement. Use field projection to retrieve only the necessary data and improve query performance.