SQL

What is SQL?

SQL (pronounced "ess-que-el") stands for Structured Query Language. SQL is used to communicate with a database. According to ANSI (American National Standards Institute), it is the standard language for relational database management systems. SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database. Some common relational database management systems that use SQL are: Oracle, Sybase, Microsoft SQL Server, Access, Ingres, etc. Although most database systems use SQL, most of them also have their own additional proprietary extensions that are usually only used on their system. However, the standard SQL commands such as "Select", "Insert", "Update", "Delete", "Create", and "Drop" can be used to accomplish almost everything that one needs to do with a database. This tutorial will provide you with the instruction on the basics of each of these commands as well as allow you to put them to practice using the SQL Interpreter.

What Is SQL?

SQL can be used to share and manage data, particularly data that is found in relational database management systems, which include data organized into tables. Multiple files, each containing tables of data, also may be related together by a common field. Using SQL, you can query, update, and reorganize data, as well as create and modify the schema (structure) of a database system and control access to its data.

A lot of nformation can be compiled in a spreadsheet such as Microsoft Excel, but SQL is intended to compile and manage data in much greater volumes. While spreadsheets can become cumbersome with too much information, SQL databases can handle millions, or even billions, of cells of data.

Using SQL, you could store data on every client your business ever worked with, from key contacts to details about sales. So, for example, if you wanted to search for every client that spent at least $5,000 with your business over the past decade, an SQL database could retrieve that information for you instantly.

How Learning SQL Works

Structured Query Language is more straightforward than other more complex programming languages. It is typically easier for beginners to learn SQL than it is for them to pick up languages such as Java, C++, PHP, or C#.

Several online resources, including free tutorials and paid distance learning courses, are available for those who have little programming experience but want to learn SQL. Formal university or community college courses also will provide a deeper understanding of the language.

• Free tutorials: W3Schools SQL Tutorial, SQLcourse.com, and Codecademy's Learn SQL and course on analyzing SQL business metrics
• Paid distance-learning courses: International Webmasters Association's (IWA) Introduction to SQL (Using Access) or Introduction to SQL (Using MySQL)
• Books on SQL for beginners: "SQL: A Beginner's Guide" and "SQL in a Nutshell"

History of SQL

The origins of SQL stretch back more than half a century. In 1969, IBM researcher Edgar F. Codd defined the relational database model, which became the basis for developing the SQL language. This model is built on common pieces of information (or “keys”) being associated with various data. For example, a username might be associated with an actual name and a telephone number.

A few years later, IBM began working on a new language for relational database management systems based on Codd’s findings. The language was originally called SEQUEL, or Structured English Query Language. Dubbed System R, the project went through a few implementations and revisions, and the name of the language changed several times before finally landing on SQL.

After beginning testing in 1978, IBM started developing commercial products, including SQL/DS (1981) and DB2 (1983). Other vendors followed suit, announcing their own commercial SQL-based offerings. These included Oracle, which released its first product in 1979, as well as Sybase and Ingres.1 2

SQL in Action: MySQL

Common software used for SQL servers includes Oracle's MySQL, perhaps the most popular program for managing SQL databases. MySQL is open-source software, which means it is free to use and is important for web developers because so much of the web and so many applications are built on databases.

Consider a music program such as iTunes, which stores music by artist, song, album, playlist, and more. As a user, you can search for music by any of those parameters and more to find what you're seeking. In order to build an app like that, you need software to manage your SQL database, and that's what MySQL does.

SQL Skills in Demand

Most organizations need someone with SQL knowledge. Salaries for SQL-based positions vary depending on job type and experience but are generally above average.

Some positions that require SQL skills include:

• Database administrator (DBA): This is someone who specializes in making sure data is being stored and managed properly and efficiently. Databases are most valuable when they allow users to retrieve desired combinations of data quickly and easily.
• Database migration engineer: This person specializes in moving data from various databases onto an SQL server.
• Data scientist: This is a position very similar to that of a data analyst, but data scientists typically are tasked with handling data in far greater volumes and accumulating it at much higher speeds.