A query in a database is a command or statement used to retrieve, filter, and manipulate data from one or more tables in a database management system (DBMS). It is a request for information from the database that follows a specific syntax and language, such as SQL (Structured Query Language).
A query can be used to perform a wide range of operations on the data, including selecting specific columns, filtering data based on criteria, sorting data, grouping data, and combining data from multiple tables through joins.
Queries can be simple or complex, depending on the complexity of the data and the purpose of the query. They can include mathematical or logical expressions, such as aggregate functions and conditional statements, to perform calculations and comparisons on the data.