SQL is an ANSI (American National Standards Institute) standard. SQL stands for Structured Query Language. This language is used to access / communicate with a database. A database is an organised collection of data usually in digital form. Though SQL was originally developed by IBM, and first made commercial by Relational Systems (now part of Oracle), almost all database software vendors support SQL while adding their own SQL extensions.
When SQL was developed originally in the 1970’s, it was called as SEE – QU –EL, for the short form of Structured English Query Language. SQL was created in such a way that, with some simple English language words that can be kept in our memory, we can query the database. Though there had been limitations, SQL remains as one of the most widely used data manipulation methods for several decades now. Some of the common RDBMS ( Relational Database Management Systems ) that use SQL are: Microsoft SQL Server (latest version – SQL Server 2008 R2) Oracle (latest version – 11 g) IBM DB2 (latest version IBM DB2 9.7), MySQL (open source database), Sybase etc.
Some of the most commonly used SQL commands are:
SQL can be broadly divided in to Data Manipulation Language ( DML) and Data Definition Language ( DDL) . Data Manipulation Commands: Select, Update, Insert, Delete etc., Create is a Data Definition Language command.
- Select – extracts data from database.
- Insert – inserts new data in to database
- Update –updates the data in database
- Delete – deletes the data from the database.
- Create – creates a new database.
The following is a typical example of a table:
|Person_Id||First Name||Last Name||City|
This table named as ‘Contributors’ have three records and four columns. If we want to select first name and last name, we use the following select statement:
SELECT First Name, Last Name from Contributors.
|First Name||Last Name|
There are good resources available on the web to teach SQL basics for beginners. Most of the business users and software programmers know the basics of SQL.
There are standards for SQL. This standardisation is coming from both ANSI and ISO (International Organization for Standardisation ). These standards are getting a number of revisions then and there. The idea behind this standardisation is to facilitate easier movement of software applications between different database systems without the need to write / re write extra codes. However, in the practical industrial scenario, we see that vendors are developing products that is not in full accordance with standards.
Expertstown has presented several advanced articles to readers in database and data base management system. This is a primer article containing basic information on SQL. And there is a lot more in store to come in future! From its commercial implementation three decades ago, SQL has grown in to big now. It is not exaggeration to say that the world’s largest software companies like Microsoft, Oracle depend on their SQL / Database server offerings. SQL plays an important role in computer industry today.