SQLlausekkeista

SQLlausekkeista, often referred to as SQL clauses, are fundamental components of Structured Query Language (SQL) statements. These clauses are keywords that instruct the database management system on how to retrieve, manipulate, or define data. Each clause serves a specific purpose within a SQL query, dictating the conditions for data selection, ordering, grouping, or modification.

Common SQL clauses include SELECT, which specifies the columns to be retrieved; FROM, which indicates the table(s) from which to retrieve data; WHERE, which filters rows based on a specified condition; GROUP BY, which groups rows that have the same values in specified columns; HAVING, which filters groups based on a specified condition; and ORDER BY, which sorts the result set in ascending or descending order.

Other important clauses are INSERT INTO, used to add new records to a table; UPDATE, used to modify existing records; and DELETE, used to remove records from a table. Data Definition Language (DDL) statements also utilize clauses like CREATE TABLE to define new tables and ALTER TABLE to modify existing ones. Understanding and correctly utilizing these SQL clauses is essential for effective database interaction and management. Their specific syntax and application vary slightly between different SQL database systems, but their core functionality remains consistent.