SQL language is a programming language that allows a relational database to be manipulated and interacted with. This language is one of the few languages that a majority of databases will be able to run off of. When SQL (structured query language) is used, the software of a database program will take commands and translate them into demands that the database will be capable of interpreting. In general, SQL is known to have three different main components. These include the data manipulation language, data definition language and data control language.
The History of SQL
SQL has been in existence since the 1970s. It was originally developed by Donald Chamberlin and Raymond Boyce. These two programmers developed the language while working for IBM. The initial version of SQL was known as SEQUEL. SQL was at first rested to both work with and seek out data that was stored using the original database system of IBM.
Further advancements on the original SQL were made throughout the 1970s, and Oracle V2 was made available as one of the first commercial implementations of SQL. IBM made further developments on the original SQL with other languages including SQL/DS and DB2.
The Syntax of SQL
SQL can be broken down into several different major elements. These include the following:
- Clauses – These are parts of the SQL language that make up certain statements or queries used to manipulate the database.
- Expressions – An expression can be used in SQL to create both scalar values an tables.
- Predicates – These aspects of SQL can either specify certain three-valued logic determinants or certain Boolean truth values. They can limit the input significance of different statements and queries.
- Queries – A query in SQL can be used to retrieve data centering on certain specifications.
- Statements – Different statements can be put into the SQL language to specify certain effects on both data and schemata. These statements can be used to dictate aspects of the program such as connections, sessions, transactions, and program flow.
The Query
The query is the most frequently seen operator in all of the SQL syntax. This query is performed using SELECT, which will be responsible for getting data from certain tables or expression used in the program. Using a query, the user of SQL is able to create descriptions on various data. This makes it so the database management system being used is able to plan, optimize, and perform certain operations necessary for the manipulation of the database program.
Related Resource: Framework
Extensions
All of SQL is designed to be used for a particular purpose. Possible purposes generally involve querying data that is found within a certain relational database. SQL is classified as a set-based language, and it is further identified as declarative as opposed to imperative. According to Tech Target, although SQL is considered to be a declarative language, certain extensions can be added to the language that can make it more procedural. One possible extension is that of control-of-flow constructs. These can make the SQL language capable of a variety of additional programmability features.
