When it comes to manipulating, storing, and returning data in a database, SQL is the way to go. Lots of different relational database management systems uses SQL such as SQL server, MySQL, MS Access, Sybase, Oracle, Postgres, and Informix. SQL can do lots of things with a database such as…
-execute queries
-retrieve data
-insert records
-update records
-delete records
-create new databases
-create new tables
-create procedures
-create views
-set permissions
To use SQL for your website, you will need a RDBMS, some server-side scripting language, and CSS / HTML.
RDBMS
RDBMS (Relational Database Management System) is used in all modern database systems. One might wonder about the difference between a RDBMS versus just a DBMS. What a RDBMS does is it stores data in table structures that connect data based on relationships. This helps keep the data organized and forms the data the way it is represented in the world. With in a RDBMS, you have tables which contain rows called records. Each row is an instance. The columns represent the attributes. For example, say you have a table called Customers. They might have the attributes name, phone number, etc. If you are looking for specific information from the Customer table, you do not want to pull all the data. SQL allows you to select for specific attributes.
SELECT name FROM Customers;
Here, the attribute name is being selected from Customers. This will return only the customer’s names from the table Customers. This is one of many examples of what makes SQL so useful.
Basics of SQL
Tables
A SQL database will consist of usually many tables. They are named on the data they will be representing.
| FirstName | LastName | Age |
|---|---|---|
| John | Smith | 26 |
| John | Smith | 26 |
| John | Smith | 26 |
SQL Statements
Most actions performed in SQL are done with SQL statements. The following is an example of a statement to get the names of customers: SELECT name FROM Customers;
Most important SQL commands
-UPDATE: update data
-DELETE: deletes data
-SELECT: pulls data
-INSERT INTO: inserts data
There are many other commands, but these are some that are seen most often.