What is SQL?

Understanding what is SQL as well as mastering SQL Basics is a must in order to become a technical project manager or successful database professional be it a Database Administrator (DBA) or a Database Developer. The reason being that most software developments require work to be done on a database, and the most common language for doing this is SQL.

Therefore whether you are a technical project manager, web professional, database developer, ecommerce developer, mobile developer or a technical architect, understanding what is SQL as well as knowledge of the SQL basics is an absolute must.

This is particularly the case where web project plans and internet developments are concerned. After all if the web programming languages like PHP and HTML are at the heart of the internet, then SQL is the internet’s backbone. Irrespective of the language in which a website is programmed, it is almost a de-facto practice to use a database for information storage and knowing SQL basics is crucial to be able to perform database interaction successfully.

It is particularly important to understand the basics of SQL whilst the software requirements specification is being detailed as well as during the software testing life cycle as this is where the problems tend to materialize.

1.0 What is SQL?

SQL stands for Structured Query Language and it’s a programming language for databases standardized by American National Standards Institute (ANSI). It is used to access and modify data for relational databases such as Oracle, MySQL and DB2 amongst others.

SQL Basics consists of queries; syntactically and semantically correct statements which can retrieve or modify data from a database. The term CRUD is often used to denote basic SQL operations – C for Create, R – Read, U for Update and D for Delete.

Though some different types of relational databases may have some minor variations for their syntax, ANSI recommends that each database must support the following major keywords – SELECT, UPDATE, INSERT and DELETE.

1.1 Tip

In terms of CRUD operations, C (Create) refers to INSERT, R (Read) refers to SELECT, U (Update) refers to UPDATE and D (Delete) refers to DELETE keyword.

2.0 What is SQL Server?

SQL Server is a database product offered by Microsoft which is widely used especially in .net and C# developments.. It is however not the only relational database which uses the SQL language.

3.0 What is SQL Databases and Tables?

The first step to understanding SQL is to understand what are databases and tables. As the name represents, a database is a collection of relevant data grouped into various logical entities called tables.

Each database can have multiple tables and each table can have multiple rows and columns. If you understand the role of rows and columns in database tables, half the battle of mastering SQL is already won by then. Columns represent the attributes/ properties of a table and rows represent the actual data.

4.0 SQL Basics and Queries

Knowing SQL Basics means the ability to interpret and write database queries. These queries are the code which enables the database to operate as required. In order to do this understanding the following queries/ statements is essential.

SELECT Statement

This is undoubtedly the most heavily used statement as far as SQL basics are concerned and it is used to fetch/ retrieve data from a single or multiple tables of a database based on some criteria. It allows ordering and grouping of results based on various parameters.

INSERT Statement

This is used to enter new data into database tables. To master SQL basics, it is an absolute necessity that you know how to enter data. This statement is very often used on website forms/ pages which prompt you to enter data.

UPDATE Statement

This is used to update the existing data in database tables.

DELETE Statement

This is used to delete the existing data in database tables.

4.1 Tip

SELECT does not modify the table structure/ data but all other statements either modify the table structure/ data so be careful in using them.

5.0 SQL Basics and Data Types

As the name implies, data types refer to the kind of data that can be stored in database table’s columns. It is crucial to understand these data types in order to be comfortable with SQL basics. Data types may be known by different names in various databases but the basic concept remains the same across all databases. Almost all databases offer the following data types – Text, Number and Date. Each may have sub data-types e.g. Number can be integer, float, double, decimal etc.

6.0 SQL Basics and Keys

Good Understanding of Keys (Primary Keys, Foreign Keys, and Composite Keys) is crucial to mastering SQL. So, what do these keys mean?

Primary Key

It represents a value (column) which is unique for every row in a table

Composite Key

It represent a combination of values (columns) which is unique for every row in a table

Foreign Key

It represents a relationship between two tables. The foreign key for a table is the primary key for the referenced table.

6.1 Tip

To learn how keys work, create test tables and play with them by creating primary, composite and foreign keys for them.

What is SQL? - Tip

Understanding what is SQL and what is SQL Server is absolutely vital for any technical project manager to understand, since database development is usually a fundamental part of the process of software development especially web related projects.