SQL-Structured Query Language

SQL 代表結構化查詢語言，它是數據庫使用的語言。

In this app you will learn SQL (Structured Query Language) by video lectures offered by professional which is free of cost and comprehensive exactly related to the topic.

Introduction of SQL(Structured Query Language)

In this article, we will provide a SQL(Structured Query Language) definition and we will explain what it is, and we will also talk about the SQL(Structured Query Language) extensions. We will also provide some examples of SQL(Structured Query Language) Syntax.

SQL(Structured Query Language) Definition

Basically, SQL stands for Structured Query Language which is basically a language used by databases. This language allows to handle the information using tables and shows a language to query these tables and other objects related (views, functions, procedures, etc.). Most of the databases like SQL(Structured Query Language) Server, Oracle, PostgreSQL, MySQL, MariaDB handle this language (with some extensions and variations) to handle the data.

With SQL(Structured Query Language) you can insert, delete, and update data. You can also create, delete, or alter database objects.

Who invented SQL(Structured Query Language)?

Edgar Frank Codd while he worked for IBM invented the relational database in the 70s. Based on that work, Donald Chamberlin and Raymond Boyce designed SQL(Structured Query Language) to manipulate data. It was initially called SEQUEL, but due to a trademark problem, it was changed to SQL(Structured Query Language). However, many people still say SEQUEL.

ANSI SQL Definition and ISO SQL Definition

The American National Standards Institute (ANSI) make SQL(Structured Query Language) a standard in 1986 and the International Organization for Standardization (ISO) makes SQL the database standard. Now all the most popular databases follow these standards with some extensions. The SQL(Structured Query Language) definition is a language to define database objects and manipulate the data.

There were several revisions to define how will be SQL(Structured Query Language), including data types, isolation levels, logical operators, syntax, data definition language syntax, data manipulation language definitions, procedures, functions, and so on.

SQL Definition for UNION, INTERSECT, EXCEPT

SQL(Structured Query Language) defined a standard syntax to create a union between 2 tables or to get the common rows (intersect) or the rows that are not common (except). The following article explains how to use them:

Extensions of the SQL definition

Each database system has its own SQL(Structured Query Language) extension. For example, SQL Server uses T-SQL that is a SQL extension. Oracle uses PL-SQL, MySQL and MariaDB use SQL/PSM (SQL and Persistent Stored Module). PSM is an ISO standard for stored procedures. Teradata and Informix use SPL and there are several different extensions used by different System Databases.

Conclusion

In this article, we explained the SQL(Structured Query Language) definition. Basically, it is a language to handle data. It was initially created to handle structured data, but even the NoSQL databases (databases that are non-relational), usually use a SQL extension to retrieve data. Big Data platforms are also using SQL extensions to handle their data, so the SQL definition will be useful for a long time.