We now move on to produce WWW pages that can manipulate databases. To do this, all we have to do is call the appropriate functions of PHP that enable us to pass SQL statements to a MySQL database.

The PHP scripts that follow use these functions:

• mysql_connect which connects to a MySQL server running on some computer supplying a username and a password to the MySQL server. For example:

  $c_result = mysql_connect("dbserver.site.com", "dxy3fab", "ind1g0");
  

  Typically, the MySQL server will be configured so that the username and password are required when the developer wishes to change a database but they can be empty strings when he/she only wishes to inspect the database:

  $c_result = mysql_connect("dbserver.site.com", "", "");
  

• mysql_select_db which chooses a database:

  $s_result = mysql_select_db("Pdcl0bjc_prices", $c_result); 
  

• mysql_query which executes a given SQL query:

  $q_result = mysql_query("SELECT * FROM consum WHERE price<1.0", $c_result);
  

• mysql_num_rows which finds out how many rows there are in the result of a query:

  $numrows = mysql_num_rows($q_result);
  

• mysql_result which returns the value of a given column of a given row of the result of a query:

  print mysql_result($q_result, $rownum, "price");