SQL

SQL

SQL (Structured Query Language) is a database computer language designed for managing data in relational database management systems (RDBMS).

SQL is a "what, now how" language, i.e. you don't specify how the database should obtain the result, merely what the result should be, for example:

-- Where more than one supplier supplies a part, display the maximum and minimum prices. 
SELECT ps_partkey, MIN(ps_supplycost), MAX(ps_supplycost)
FROM partsupp
GROUP BY ps_partkey
HAVING COUNT(*) > 1
ORDER BY ps_partkey

Many excellent SQL reference books already exist and so this page does not attempt to explain all the details of the language; choosing instead to focus on the key aspects and definitions.

These pages also use examples to show how SQL can be used to solve more complex problems. Their solutions demonstrate how various statement components can be combined to achieve the required results without the need to build intermediate tables or views, or resort to additional pre- or post-processing on the client.