Intro to SQL & Relational Databases

SQL (pronounced S-Q-L or sequel) is a back-end programming language explicitly designed to work with relational database management systems (RDBMS). SQL stands for Structured Queried Language and is used to communicate with databases. SQL couldn’t be used to build a mobile app or web application, for example.

Understanding Databases

In the world of computer programming, databases are used to store information. Each database is used with a “query” language to both store and retrieve information in the database. SQL is the standard programming language for RDBMS.

What Does SQL Do?

SQL’s primary purposes are data management and analysis. With SQL code, you can perform a variety of functions related to creating tables (multiple tables stored together form a database) and managing data in tables by storing and querying information in these tables. At the advanced levels, SQL involves creating temporary tables, automating database functions, and cleaning data within tables. In a SQL course, you will learn how to do the following tasks:

• Create databases
• Make new tables
• Insert new records
• Add attributes to records
• Join tables
• Filter and sort data
• Query data
• Save queries and data management procedures
• Manipulate data with table views
• Write logic statements and variables
• Convert output data to a user-friendly format
• Export data to external applications

Which Database Applications Are Used with SQL?

SQL serves as the standard database language for a variety of proprietary database management systems. Many companies use Microsoft SQL Server (also referred to as MSSQL or SQL Server), which is the backbone of Microsoft websites including Bing, Microsoft.com, and MSN.com. MySQL, Oracle, PostgreSQL, and Microsoft Access databases also use SQL.

SQL is a standard language, which means some commands are standard across the wide variety of relational database management systems. SQL first became an accepted standard by ANSI (American National Standards Institute) in 1986 and later ISO (International Organization for Standardization) in 1987. Despite this standard, most SQL databases use a variety of proprietary SQL languages (commonly referred to as extensions) to manipulate data.

In the case of extensions of SQL, each database has different names for data. It’s important to define each data type according to the specifications set out for that particular database. The following chart lists an example of how one datatype is used in various SQL databases.

When working with different databases, it’s always important to check the documentation. Each database has slightly different documentation for combination strings consisting of text and numbers. In addition to the different naming conventions, each table has distinct size or width requirements and varies slightly in the type of data that it can hold.

How is SQL Used in a Website?

SQL is just one component of building a website that stores data. Front-end languages—HTML, CSS, and JavaScript develop and design the website structure. A database such as Microsoft Sequel Server, MS Access, or MySQL stores data. SQL stores and retrieves the data in a website. Finally, a back-end language such as PHP communicates with the database based on input from the user.

Benefits and Disadvantages of SQL

At the time it first surfaced in the mainstream in the early 1980s, SQL was the primary database language for its ease of use. It was much easier and faster to train developers to code in and use SQL than its predecessor Codasyl. However, SQL doesn’t come without its faults. The most significant complaint about SQL is the learning curve involved in the logic behind writing good queries and understanding the design of the relational database. Also, the limited number of standardized commands means you’ll need to learn different commands for MySQL, MSSQL, and each database management system.