PHP - MySQL Introduction
MySQL is a database. The data in MySQL is stored in database objects called tables. A table is a collection 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 |
|---|
| Dayendra | Oka | Nusa Dua | Denpasar |
| Mahendra | Oka | Imam Bonjol | Denpasar |
| Rajendra | Oka | Teuku Umar | Denpasar |
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 |
|---|
| Dayendra |
| Mahendra |
| Rajendra |
