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PHP Script Tips - Working with MySQL Database

By: FYICenter.com

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How To Create a Database?

A database in a MySQL server is a logical container used to group tables and other data objects together as a unit. If you are a the administrator of the server, you can create and delete databases using the CREATE/DROP DATABASE statements. The following PHP script shows you how to create and drop an database called "fyi":

<?php
  $con = mysql_connect('localhost');
  $sql = 'CREATE DATABASE fyi';
  if (mysql_query($sql, $con)) {
    print("Database fyi created.\n");
  } else {
    print("Database creation failed.\n");
  }

  $sql = 'DROP DATABASE fyi';
  if (mysql_query($sql, $con)) {
    print("Database fyi dropped.\n");
  } else {
    print("Database drop failed.\n");
  }
  mysql_close($con); 
?>

If you run this script, you will get something like this:

Database fyi created.
Database fyi dropped.

How To Select an Exiting Database?

The first thing after you have created a connection object to the MySQL server is to select the database where your tables are locate, by using the mysql_select_db() function. If your MySQL server is offered by your Web hosting company, they will assign a database to you and provide you the database name. You should use this name to select your database as your current database. The following script shows you how to select a database called "fyi". It also shows you how to put all the database connection statements in a single include file, and re-use it in all of your PHP pages.

Create the include file, connect.php, with the following statements:

<?php
  $server = "localhost";
  $username = "";
  $password = "";
  $database = "fyi";
  $con = mysql_connect($server, $username, $password);
  mysql_select_db($database);
?>

To test this database connection and selection include file, try the following script:

<?php
  include "mysql_connection.php";

  $sql = 'SHOW TABLES';
  if ($rs = mysql_query($sql, $con)) {
    print(mysql_num_rows($rs) . " tables in the database.\n");
  } else {
    print("SHOW TABLES failed.\n");
  }

  mysql_close($con); 
?>

You will get something like this:

0 tables in the database.

How To Run a SQL Statement?

You can run any types of SQL statements through the mysql_query() function. It takes the SQL statement as a string and returns different types of data depending on the SQL statement type and execution status:

• Returning FALSE, if the execution failed.
• Returning a result set object, if the execution is successful on a SELECT statement or other statement returning multiple rows of data.
• Returning TRUE, if the execution is successful on other statements.

Here is a good example of running a SQL statement with the mysql_query() function:

<?php
  include "mysql_connection.php";

  $sql = 'SELECT sysdate() FROM dual';
  $rs = mysql_query($sql, $con);
  $row = mysql_fetch_array($rs);
  print("Database current time: ". $row[0] ."\n");

  mysql_close($con); 
?>

If you run this script, you will get something like this:

Database current time: 2006-02-26 21:34:57

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