What is the difference between MongoDB and SQL DB?
SQL databases are used to store structured data while NoSQL databases like MongoDB are used to save unstructured data. MongoDB is used to save unstructured data in JSON format. MongoDB does not support advanced analytics and joins like SQL databases support.
Is MongoDB a good DB?
MongoDB has become one of the most wanted databases in the world because it makes it easy for developers to store, manage, and retrieve data when creating applications with most programming languages.
What is difference between relational and nonrelational database?
To summarize the difference between the relational and non-relational databases: relational databases store data in rows and columns like a spreadsheet while non-relational databases store data don’t, using a storage model (one of four) that is best suited for the type of data it’s storing.
What is the difference between $exists and null in MongoDB?
When the is true, the $exists operator matches the documents that contain the field with any value including null. If the is false, the $exists operator matches the documents that don’t contain the field. The MongoDB $exists doesn’t correspond to the EXISTS operator in SQL.
What is the $exists operator in MongoDB?
Summary: in this tutorial, you’ll learn how to use the MongoDB $exists operator. The $exists is an element query operator that has the following syntax: When the is true, the $exists operator matches the documents that contain the field with any value including null.
What is the difference between $exists and $boolean_value?
When the is true, the $exists operator matches the documents that contain the field with any value including null. If the is false, the $exists operator matches the documents that don’t contain the field.
How do I query for null or missing fields in MongoDB?
Starting in MongoDB 4.2, users can no longer use the query filter $type: 0 as a synonym for $exists:false. To query for null or missing fields, see Query for Null or Missing Fields. Consider the following example: This query will select all documents in the inventory collection where the qty field exists and its value does not equal 5 or 15.