What Is SQL and How Is It Used?
Structured Query Language, or SQL, is a programming language specifically created for databases. It’s the most widely-implemented database language; everyone has a need for SQL.
SQL is used to share and manage data, particularly data that is found in relational database management systems - data is organized into tables, and multiple files, each containing tables of data, may be related together by a common field.
Using SQL, you can query (request information from databases), update and reorganize data, as well as create and modify the schema (structure) of a database system, and control access to the data. Common software used for SQL servers include Microsoft Access, MySQL, and Oracle.
History of SQL
In 1969, IBM researcher Edgar F. Codd defined the relational database model, which became the basis for developing the SQL language. Put simply, the relational database model is having a common piece of information (or a “key”) associated with various data. An example is a username being associated with both your real name and 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. This project, dubbed System/R, went through a few implementations and revisions, and the name of the language was changed a few times before it was finally called SQL.
After beginning testing on SQL 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, who released its first product in 1979, as well as Sybase and Ingres.
SQL is easier for beginners to learn than it is for them to pick up programming languages like Java, C++, PHP or C#.
If you want to learn SQL, but have very little existing programming background, you may benefit from trying it out using one of the resources below, then taking a deeper dive with a formal university or community college course. Otherwise, you could take advantage of many free online tutorials or paid distance-learning courses.
Here are some examples of free tutorials:
SQLcourse.com (introductory SQL tutorial)
I've taken IWA courses before. The SQL ones are only four weeks long, but they're more structured than self-learning tutorials because the courses are instructor-led and involve completing specific assignments once a week. You'd be surprised how much you can learn in such a short timespan.
Useful books on SQL for beginners include:
Check your local library to see if they carry these or other introductory SQL books.
SQL Skills are Desirable
As mentioned before, almost everyone needs someone with SQL knowledge in their organization.
According to Gooroo, 50,705 jobs were advertised in 2015 that required SQL knowledge, and the median salary for a position that requires SQL knowledge is $81,632.
Here are some of the types of positions that require SQL skills: