PHP MySQL Introduction

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MySQL is the most popular open-source database system.
What is MySQL?

MySQL is a database.


The data in MySQL is stored in database objects called tables.
A table is a collections of related data entries and it consists of columns and rows.


Databases are useful when storing information categorically. A company may have a database with the following tables: "Employees", "Products", "Customers" and "Orders".




Database Tables

A database most often contains one or more tables. Each table is identified by a name (e.g. "Customers" or "Orders"). Tables contain records (rows) with data.


Below is an example of a table called "Persons":




LastName FirstName Address City Hansen Ola Timoteivn 10 Sandnes Svendson Tove Borgvn 23 Sandnes Pettersen Kari Storgt 20 Stavanger The table above contains three records (one for each person) and four columns (LastName, FirstName, Address, and City).



Queries

A query is a question or a request.
With MySQL, we can query a database for specific information and have a recordset returned.


Look at the following query:




SELECT LastName FROM Persons



The query above selects all the data in the "LastName" column from the "Persons" table, and will return a recordset like this:





LastName Hansen Svendson Pettersen

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