A server with a regular, non-root user with sudo privileges and a firewall configured with UFW.You will also learn what cursors are and how to use them within the MongoDB shell. In this tutorial, you’ll learn how to query MongoDB collections using a different range of filters and conditions. MongoDB provides a robust query mechanism for defining filtering criteria when retrieving documents. Similar to how you would find your holiday destination by selecting a range of filters on a booking website, such as distance from the seaside, pet-friendliness, a pool, and nearby parking, you can precisely query MongoDB to find exactly the documents you need. Instead, you’ll more likely want to only retrieve documents that satisfy one or more particular conditions. Regardless of how complex your documents are or how many you have, most often you won’t need to review the data in all of them at once. Others might be highly complex, containing dozens of fields of different types, arrays holding multiple values, and even other documents nested within the larger structure. Some might be relatively small and contain only a few entries, like items in a shopping list. Introductionĭocuments stored in a MongoDB database can vary widely. For example, if you wish to see the Gaurav Mandes data, you can add a specific attribute to the find() to fetch the data of Gaurav Mandes from that particular database.Įxample: db.writers.The author selected the Open Internet/Free Speech Fund to receive a donation as part of the Write for DOnations program. It is also possible to filter your results by giving or adding some specific criteria in which you are interested to. Here is how they can be implemented: Filtering Criteria in MongoDB Queries Syntax: db.collection_name.find().pretty() The pretty() method: This method is used for giving a proper format to the output extracted by the query. Various other options can be used to make the query specific. The basic syntax for using this method is: The find() method: This method is used for querying data from a MongoDB collection.Methods for Performing Queries in MongoDB This is where the queries of a database language become useful. Let us assume a situation where your database has an employee table, and you wish to track the sales performance ID, so you have to write a query to ask your database to fetch for you the list of all the sales performance with the highest sales data in the top. Queries can be explained by taking a suitable example: Every query associated with the database system is associated with any particular language (such as SQL for structured data, MongoDB for unstructured data). What Is a Database Query?Ī query in a database system is a command that is used for extracting data from a database and display it in a readable form. In this chapter, you will learn about the different ways of how queries can be made using MongoDB. When your database is having all the data fed into it, and you want to retrieve the data by executing some command, MongoDB allows you to do that. Queries are another essential element of a database system. MongoDB - Overview MongoDB - Introduction to NoSQL MongoDB - Benefits of Using NoSQL MongoDB - History MongoDB - Environment Setup MongoDB - Database Create and Drop MongoDB - Data Types MongoDB - Create Collection MongoDB - Drop Collection MongoDB - Insert Documents MongoDB - Query Operations MongoDB - Projection Queries MongoDB - Limiting Query Result MongoDB - Update Documents MongoDB - Delete Documents MongoDB - Concept of Aggregation MongoDB - Sorting MongoDB - Indexing MongoDB - Advanced Indexing MongoDB - Concept of Replication MongoDB - Concept of Sharding MongoDB - Export MongoDB - Data Backup and Restore MongoDB - Regular Expression
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