The Role of SQL
The term Structured Query Language is, actually, rather a misnomer.
That’s down to the fact that SQL is way more than a mere query tool, though retrieving data from a computer database was SQL’s originally intended purposes and it still is the most important function for which the database language is employed by almost all leading IT enterprises.
However, having said that, SQL is extensively employed to control all important functions a user can perform through a database management system, including:
- Data definition. SQL allows a database administrator to define the organization and structure of stored data and the relationships amongst different stored data items.
- Data retrieval. SQL helps an application or user program to fetch stored data from a computer database and make use of it.
- Data manipulation. SQL helps an application or user program to update the computer database by removing old data, modifying hitherto stored data, and adding new data.
- Access control. SQL can also be deployed for restricting user permission for adding, retrieving or modifying stored data, thence protecting data from unauthorized access.
- Data sharing. SQL is used by concurrent users to coordinate data sharing to ensure the users don’t interfere with one another.
- Data integrity. SQL is also used in a database to define integrity constraints to prevent data corruption by system failure or inconsistent update.
SQL is, therefore, a comprehensive language and a resourceful, powerful tool to control and interact with a computer database system.
Second, SQL is essentially a sub-language
SQL can’t exactly be termed as a complete language like C, C++, Java, Python or COBOL. In SQL, there’s no IF statement to test conditions; also it does not have any FOR, GOTO, or DO statement to control program flow.
SQL is, instead, a database sub-language that comprises of nearly forty statements specialized to perform database management tasks.
A user can embed these SQL statements in any other complete language like C or COBOL for extending the compatibility of that language with the database.
As an alternate, a programmer can explicitly sent them to a database system for processing, by using a CLI (Call Level Interface) from a computer language like C, C++ or Java.
Finally, SQL isn’t predominantly a structured language, particularly when equated to extremely structured languages, for example Pascal, Java, or C. SQL statements instead look like English sentences, completed by "noise words" that essentially add no meaning to the statement and are used only for making the sentence more readable.
Moreover, the SQL language has a few inconsistencies, along with some special rules to avoid the construction of SQL statements that look fairly legal but do not generally make much sense. Regardless of these widespread inaccuracies in its name, SQL has surfaced as the standard relational database language. SQL is relatively easy to learn yet an immensely powerful language at the same time.
The Role of SQL
SQL is not itself a standalone product or a complete database. You cannot step into a computer store and ask for "SQL." Instead, SQL is an integral part of a database management system, a language and a tool to communicate with the DBMS.