Updating Your Data | Spring Into PHP 5

When your data changes, it's easy to update your database with the appropriate SQL statement. Here's an examplesay that someone buys a pear, which would change the number of pears in our database from 235 to 234. You can make that change by connecting to MySQL and selecting the produce database:

 $connection = mysql_connect("localhost","root","")     or die ("Couldn't connect to server"); $db = mysql_select_db("produce",$connection)     or die ("Couldn't select database");

Now you can update the value in the pears row of the fruit table like this, where we're setting the value of the number field to 234:

 $query = "UPDATE fruit SET number = 234 WHERE name = 'pears'";          .          .          .

Then you just execute that query like this:

 $query = "UPDATE fruit SET number = 234 WHERE name = 'pears'"; $result = mysql_query($query)     or die("Query failed: ".mysql_error());

That's all it takes; you can see all this code in phpdataupdate.php, Example 8-2.

Example 8-2. Updating database data, phpdataupdate.php

 <HTML>     <HEAD>         <TITLE>             Updating database data         </TITLE>     </HEAD>     <BODY>         <CENTER>             <H1>Updating database data</H1>             <?php                  $connection = mysql_connect("localhost","root","")                      or die ("Couldn't connect to server");                  $db = mysql_select_db("produce",$connection)                      or die ("Couldn't select database");                  $query = "UPDATE fruit SET number = 234 WHERE name =                      'pears'";                  $result = mysql_query($query)                       or die("Query failed: ".mysql_error());                  $query = "SELECT * FROM fruit";                  $result = mysql_query($query)                       or die("Query failed: " . mysql_error());                  echo "<TABLE BORDER='1'>";                  echo "<TR>";                  echo "<TH>Name</TH><TH>Number</TH>";                  echo "</TR>";                  while ($row = mysql_fetch_array($result))                  {                      echo "<TR>";                      echo "<TD>", $row['name'], "</TD><TD>",                                   $row['number'], "</TD>";                      echo "</TR>";                  }                  echo "</TABLE>";                  mysql_close($connection);              ?>          </CENTER>     </BODY> </HTML>

That's all you need; you can see the results in the fruit table in Figure 8-2, where the number of pears has been updated from 235 to 234.

Figure 8-2. Updating data.