Query Language definition
A Query Language is a computer language. It’s for retrieving specific information from databases and other structured data systems. Users or software request information in a structured, precise manner and receive output.
A query language has commands for actions like:
- Selecting Data: Retrieving specific information from a database.
- Updating Data: Modifying existing data within a database.
- Inserting Data: Adding new data to a database.
- Deleting Data: Removing data from a database.
- Creating and Modifying Schemas: Defining or changing the structure of a database.
- Controlling Access: Managing who has permission to perform certain actions.
Types of query languages:
- XQuery: Used for XML data.
- SPARQL: Used for querying RDF (Resource Description Framework) data stores.
- CQL (Cassandra Query Language): Similar to SQL, but designed for Apache Cassandra databases.
- MDX (MultiDimensional eXpressions): Used for OLAP (Online Analytical Processing) databases.
- GraphQL: A query language for APIs, not databases, but it allows clients to request only the data they need.