Language Elements
The SQL language is subdivided into several language elements, including:
- Clauses, which are constituent components of statements and queries. (In some cases, these are optional.)
- Expressions, which can produce either scalar values or tables consisting of columns and rows of data.
- Predicates, which specify conditions that can be evaluated to SQL three-valued logic (3VL) or Boolean (true/false/unknown) truth values and which are used to limit the effects of statements and queries, or to change program flow.
- Queries, which retrieve the data based on specific criteria. This is the most important element of SQL.
- Statements, which may have a persistent effect on schemata and data, or which may control transactions, program flow, connections, sessions, or diagnostics.
- SQL statements also include the semicolon (";") statement terminator. Though not required on every platform, it is defined as a standard part of the SQL grammar.
- Insignificant whitespace is generally ignored in SQL statements and queries, making it easier to format SQL code for readability.
Read more about this topic: SQL
Famous quotes containing the words language and/or elements:
“Just as language has no longer anything in common with the thing it names, so the movements of most of the people who live in cities have lost their connexion with the earth; they hang, as it were, in the air, hover in all directions, and find no place where they can settle.”
—Rainer Maria Rilke (1875–1926)
“There surely is a being who presides over the universe; and who, with infinite wisdom and power, has reduced the jarring elements into just order and proportion. Let speculative reasoners dispute, how far this beneficent being extends his care, and whether he prolongs our existence beyond the grave, in order to bestow on virtue its just reward, and render it fully triumphant.”
—David Hume (1711–1776)