SQL Concepts

Programming is a great career choice and database development and programming are integral part of this career path. With the advancement in Big Data, many people choose to become database professionals, as job security, prospects and salaries are great in this profession.

If you are employed in IT, even not as a database professional, it's always a good idea to have basic knowledge what is a relational database, what is SQL, and how simple SQL commands work. This article should give you a starting point in your quest for becoming the next great database professional.

Databases and Database Tables

You've undoubtedly heard the term database, which usually refers to a relational database management system like MySQL, Oracle, or Microsoft SQL Server. These systems are used to store and access information in a tabular format (in database tables similar to an excel sheet).

SQL

SQL is the language used to work with data stored in databases. There are four major operations you can do with data using SQL:

Here are the 4 commands used to achieve the operations listed above:

SQL INSERT - The INSERT statement is the one you can use when you need to save data in your database tables. The statement is simple and it looks like the example below:

INSERT INTO TableName_1 (ColumnName_1, ColumnName_2, ColumnName_3) VALUES (Value_1, Value_2, Value_3)

This statement saved the 3 values in a table called TableName_1, in their respective columns. Once the statement is executed the data is persisted in the database. This article offers more information on the topic.

SQL SELECT - To read data stored in a database you use the SQL SELECT command. Here is an example of a SQL SELECT:

SELECT * FROM TableName_1

This command will retrieve all the data stored in the table called TableName_1. You can find more information on SQL SELECT here.

SQL UPDATE - To change information persisted in a database, you will have to use the SQL UPDATE command. Here is how to use this important command:

UPDATE TableName_1 SET ColumnName_1 = NewValue_1

With this you will assign a new value to the ColumnName_1 for all rows in the table TableName_1. The update statement can update many columns at once, but this is a topic for another article.

SQL DELETE - If you no longer need one or more of your records saved in a database you can use the DELETE keyword to remove it from the database. This command is straightforward and works like this:

DELETE FROM TableName_1

This statement will delete all records from your TableName_1. You can learn more about deleting data at http://www.sqlclauses.com.