select

Select is a verb meaning to choose from a set. In computing and information technology, it also denotes specific constructs that retrieve, filter, or coordinate data, events, or communications. The term appears across programming languages, databases, and user interfaces and often denotes an operation that narrows a larger set to a smaller, relevant subset.

In SQL, the SELECT statement retrieves data from one or more tables. It forms the core of data querying, enabling projection (choosing columns), filtering (WHERE), sorting (ORDER BY), aggregation, and joins to combine related data. Variants such as SELECT DISTINCT return unique results, and subqueries allow nested data retrieval.

In HTML forms, the select element creates a dropdown list from which users choose an option. Each option is an option element; a select can allow single or multiple selections and is included in a form submission via its name attribute.

In operating systems, the select system call monitors multiple file descriptors to determine which are ready for input or output. It enables basic I/O multiplexing, allowing a program to wait for activity on several streams at once. It has limits on the number of descriptors and is increasingly supplemented or replaced by poll, epoll, or kqueue in modern systems.

In the Go programming language, select is a control structure that waits on multiple channel operations and proceeds with whichever becomes ready first. It supports default cases and timeouts to implement nonblocking synchronization and coordination between concurrent processes.

Python’s select module provides access to the underlying select function for multiplexed I/O on Unix-like systems, commonly used to build event-driven networks and servers.