PHP
By Web Monkey
Page 1 — Getting Loopy
--------------------------------------------------------------------------------
In this lesson, we're going to dive right in and create some
simple yet useful pages using PHP and MySQL. Let's start by
displaying the database we created yesterday, but with a little
more panache.
First, let's query our database using the following code.
<html>
<body>
<?php
$db
= mysql_connect("localhost", "root");
mysql_select_db("mydb",$db);
$result
= mysql_query("SELECT * FROM employees",$db);
echo
"<table border=1>\n";
echo
"<tr><td>Name</td><td>Position</tr>\n";
while
($myrow = mysql_fetch_row($result)) {
printf("<tr><td>%s
%s</td><td>%s</td></tr>\n",
$myrow[1], $myrow[2], $myrow[3]);
}
echo
"</table>\n";
?>
</body>
</html>
You probably noticed that we introduced a couple of new features
here. Most obvious is the while() loop. The loop says that
as long as there are new rows of data to be grabbed (using
the mysql_fetch_row() function), assign that row to the $myrow
variable. Then execute the instructions between the curly
brackets ({}). Take a look for a second, and this should make
sense.
The mysql_fetch_row() function bears a closer look. One small
problem with mysql_fetch_row() is that it returns an array
that supports only numeric references to the individual fields.
So the first field is referred to as 0, the second as 1, and
so on. With complex queries this can become something of a
nightmare.
Now let's examine the loop in more detail. The first few
lines you'll recognize from the example in Lesson 1. Then
in the while() loop we fetch a row from the result and assign
it to the array $myrow. Then we print the contents of the
array on the screen with the printf function. After that it
loops around again, and another row is assigned to $myrow.
It will do this until it runs out of rows to grab.
The great thing about a while() loop is that if your query
returns no records, you won't get an error message. The first
time through there won't be any data to assign to $myrow,
and the program will just move on.
But if the query returns no data, we have no way of letting
the user know, and we should probably provide some sort of
message. This is possible, so let's do it.
next page»
|
