So to do this we use the function mysql_list_fields to grab the fields out of a table and run through them with a for loop until we find the one we are looking for – using the function mysql_field_name, in which case we return true. If we don’t find it, the function returns false.

<?php

function fieldExists($table,$field)
{

global $db; // DATABASE NAME
// This function is made to have a mysql connection previously established. You can pass the database name globally like this.

$tableFields = mysql_list_fields($db,$table);

for($i=0;$i<mysql_num_fields($tableFields);$i++){
// Run loop through fields.

if(mysql_field_name($tableFields, $i) == $field){
return true;
// We found the field we were looking for. Return true.
}

}
// No return otherwise, false.

}

?>

And it’s that easy!

If the function fails it will return false along with an error generated. You can hide the error message by adding an “@” in front of the function name.

Syntax

fopen(filename, mode, include_path, context);

Parameters

filename (String | Required)

This specifies the URL or file to open. Example: “./files/myfile.zip“.

mode (String | Required)

The type of access you are requesting for the file.

These are the valid access modes:

include_path (Boolean | Optional)

This can be set to 1 or TRUE if you want to search for the requested file in the include path, also.

context (String | Optional)

Defines the context of the file stream. This is a set of options that change the behavior of the stream.

Originally posted at w3schools.com:

Note: When writing to a text file, be sure to use the correct line-ending character! Unix systems use \n, Windows systems use \r\n, and Macintosh systems use \r as the line ending character. Windows offers a translation flag (‘t’) which will translate \n to \r\n when working with the file. You can also use ‘b’ to force binary mode. To use these flags, specify either ‘b’ or ‘t’ as the last character of the mode parameter.

Here I showed you how to upload a file from a URL using this function.

Example:

$filename = "./images/myimage.jpg";

$file = fopen($filename,"r");

if($file){
echo "We have the file.";
} else {
echo "File not found.";
}

Here is the syntax for this function:

Syntax

date(format,timestamp);

Parameters:

format
This parameter determines the format and how the date will read.

For example: “Saturday, Nov. 16th 2009” would be the following code:

$timestamp = time();
date("l, M. jS Y",$timestamp);

timestamp
This parameter is the timestamp you want to use to format a date from. This timestamp is a number of seconds since a certain date, since we used the current timestamp of time() we are making the date for the current time.

We’ll break down our example to see what each set of letters represents as part of the date’s format.

• l – day of the week, textual, long; i.e. ‘Friday’
• M – month, textual, 3 letters; i.e. ‘Jan’
• j – day of the month without leading zeros; i.e. ’1′ to ’31′
• S – English ordinal suffix, textual, 2 characters; i.e. ‘th’,‘nd’
• Y – year, 4 digits; i.e. ’1999′

View the complete date format reference here.

Here is the code:

function ordinalize($int){
if(in_array(($int % 100),range(11,13))){
return $int . "th";
} else {
switch(($int % 10)){
case 1:
return $int . "st";
break;
case 2:
return $int . "nd";
break;
case 3:
return $int . "rd";
break;
default:
return $int . "th";
break;
}
}
}

Basically the function first checks if the number is in the range of 11-13, and if so it returns the number with “th” attached (11th, 12th, 13th). If it is not in this range it checks the remainder of the number divided by 10.

So let’s say our number was 34. 10 goes into 34 three times, with a remainder of 4. Now the function runs this value against three cases, those being 1, 2, and 3. Since it is not one of them, the default value is used, which is “th.” Thus returning “4th.”

Example input:

3
10
999

Example output:

3rd
10th
999th

Enjoy!

Before we can grab anything from a mysql database we have to connect to it. Find how to connect to a mysql database here.

Let’s make our mysql query first:

<?php
// index.php
// Connect to mysql database here!
$sql = mysql_query("SELECT * FROM table1 ORDER BY id DESC") or die(mysql_error());
?>

This will grab all the rows in “table1″ ordered by the value of “id” descending. You can make this query whatever you want whether you want it ordered differently or with other requirements, etc. Now we will just make a <select> inside of a HTML form that holds each of these values as a option.

<html>
<head>
<title>Categories</title>
</head>
<body>
<form action="./index.php?do=nav" method="post">
<strong>Category:</strong> <select name="catid" style="width:250px">

Here is where we will insert our PHP code to call the returned rows of our Mysql query and display them as HTML <option> tags inside of the <select> tag.

<?php
// Display mysql rows
if(mysql_num_rows($sql) > 0){
// We have some results!
while($row = mysql_fetch_array($sql)){
echo "<option value=\"".$row["id"]."\">".$row["title"]."</option>";
}
}
else {
echo "<option value=\"0\">No categories found.</option>";
}
?>

Now we close up our HTML and see the finished result!

</select> <input type="submit" value="Go!" name="submit" />
</form>
</body>
</html>

If you have rows returned in you mysql query you will have a HTML drop down that looks like this:

This HTML form is being submitted to “index.php?do=nav.” Of course you can point this where ever you want to do whatever you want with it, but let’s say we want to have it direct you to a category with PHP. So we are going to run a function on index.php?do=nav that will redirect the viewer to the category.

<?php
// Top of index.php
if(isset($_GET["do"]) && $_GET["do"] == "nav"){
// Form submitted
if($_POST["submit"] && ((int)$_POST["catid"])){
// Redirect them to the new page.
header("Location: ./category?id=".$_POST["catid"]."");
}
}
?>

Here is the syntax for this function:

Syntax

error_reporting(report_level);

The report_level parameter is optional and specifies what report level to report for the current script. This can be set by its numeric value or its constant name, however for future versions of PHP it is recommended you use the constant name rather than the numeric value.

Report Levels

Here is an example of the error_reporting function in PHP:

<?php
//Disable error reporting
error_reporting(0);

//Report runtime and notice errors
error_reporting(E_ERROR | E_NOTICE);

//Report all errors
error_reporting(E_ALL);
?>

Here is our function, take a look and see if you can tell what the output of the function will be:

<?php

function func1(){

}

$var = func1();
echo $var;

?>

The output is nothing right now. haha So if you thought it was anything but nothing, that’s wrong. The function has no code in it whatsoever right now, and the variable “$var” is set to equal the returned value of the function “func1().” Since the function does nothing, $var is equal to nothing. Easy enough. Now let’s work with some variables.

<?php

function func1($var){
return $var; // returning the exact value of $var.
}

$var = func1("hello"); // $var is equal to the function func1() with parameter "hello"
echo $var;

?>

Now, we have a parameter to our PHP function. A parameter is any variable that is defined within the function’s parentheses. You can have many parameters in your functions – seperated by commas – but it is  a good idea to keep your functions organized and simple to their purpose. So we have $var as a parameter to func1(). You can use these to submit values through a function and work with them inside the function to return a different or desired value. Right now, the function func1() is just returning $var. So whatever is put through as $var initially, will be returned back as it was.

So this code will result in the output:

hello

Let’s say we want to have a global variable we can use in several functions. Global variables are defined as such within a function as previously defined variables outside the function. In the following code we’ll define $name as “Brian” and use it in two functions.

<?php

$name = "Brian";

function hello(){
global $name;
return "Hello ".$name."!";
}

function goodbye(){
global $name;
return "Goodbye ".$name."!";
}

$hello = hello();
$goodbye = goodbye();

echo $hello;
echo "<br/>";
echo $goodbye;

?>

The output of this code will be:

Hello Brian!
Goodbye Brian!

You can use global variables with PHP pages you include on other PHP pages. For example if you have variables defined on one PHP page, in this example “variables.php,” you can call that page to another and globally define variables in your functions to work with them and return what you like.

Variables.php:

<?php

$name = "Brian";
$website = "bgallz.org";

?>

Now on our page we are working on, we’ll call it “display.php,” we’ll call the page variables.php and use these variables in functions.

Display.php:

<?php

include("variables.php") or die("Could not find variables.php");

function hello(){
global $name;
global $website;

return "Hello ".$name."! Thanks for visiting ".$website."";

}

$var = hello();
echo $var;

?>

The output of this code will be:

Hello Brian! Thanks for visiting bgallz.org.

We must be connected to a Mysql database in order to submit the value(s) to the database. You can see how to connect to a mysql database here.

For example, lets say we want to capture the current time of when a form is submitted:

<?php

if($_POST["submit"]){
// form is submitted
$username = trim($_POST["username"];
$password = md5(trim($_POST["password"]));
// trim the values
$time = time(); // capture the current timestamp to record the time.

// connect to mysql database here!
// granted we are already connected to a mysql database, submit the query
$sql = mysql_query("INSERT INTO users (username,password,timestamp) VALUES ('$username','$password','$time')") or die(mysql_error());
}

// username,password, and time submitted to the database

If we wanted to grab the time that a user is submittted to the database (their registration date/time) we would just use a Mysql query to select the timestamp where the Username field matches a specified value. We will use the date() function to echo the timestamp into a date format. We will use the m/d/Y format:

• d – Represents the day of the month (01 to 31)
• m – Represents a month (01 to 12)
• Y – Represents a year (in four digits)

View a complete list of the PHP date() format list here!

Like so:

<?php
$sql = mysql_query("SELECT timestamp AS time FROM users WHERE username = '$username'") or die(mysql_error());
if(mysql_num_rows($sql) > 0){
$row = mysql_fetch_assoc($sql);
echo "You joined on: ".date("m/d/Y",$row['time']).".";
} else {
echo "User has not joined!";
}
?>

This will output the code as such:

You joined on: 05/31/2010.

<?php

switch($var){

case "blue":
echo "You have selected the color blue.";
break;

case "green":
echo "You have selected the color green.";
break;

case "red":
echo "You have selected the color red.";
break;

case "yellow":
echo "You have selected the color yellow.";
break;

default:
echo "You have not chosen a color.";

}
?>

You can use this with forms and such to determine an action based on a submitted value as well! Here is an example using the switch() function in a form:

<form action="submit.php" method="post">
Select your gender: <select name="gender">
<option value="">Select one...</option>
<option value="male">Male</option>
<option value="female">Female</option></select>
<input type="submit" name="submit" value="Submit" />
</form>

Now on our PHP side of the script (submit.php) we will use the switch() function to evaluate the value.

<?php

// submit.php

if($_POST['submit']){

$value = $_POST['gender'];
switch($value){

case "male":
echo "You are male. Thank you.";
break;

case "female":
echo "You are female. Thank you.";
break;

default:
echo "Please choose your gender.";

}

}

?>