nosql-1.md

01 — Finding Data (The Basics)

Goal: Look up a single specific record, like a user by their email.

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Concept Comparison

Feature	SQL	MongoDB
Concept	SELECT * with LIMIT 1	.findOne() method
Returns	One row	One document (JSON object)

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SQL Way

SELECT *
FROM Users
WHERE email = 'jane@example.com'
LIMIT 1;

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MongoDB Way

db.users.findOne({ email: "jane@example.com" });

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🔍 Breaking It Down

db         →  the database connection
.users     →  the collection (like a table)
.findOne() →  returns the FIRST match only
{ ... }    →  the filter (like WHERE)

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💡 Notes

• findOne() returns null if nothing matches — not an error.
• To find multiple documents, use .find() instead (see next section).
• MongoDB automatically assigns every document a unique _id field.