You really need only one field in the subscribers table: to hold the email address of the user. However, you should have an ID field just for consistency among your tables, and also because referencing an ID is a lot simpler than referencing a long email address in where clauses. So, in this case, your MySQL query would look something like
mysql> create table subscribers (
-> id int not null primary key auto_increment, -> email varchar (150) unique not null -> );Query OK, 0 rows affected (0.00 sec) Note the use of unique in the field definition for email. This means that although id is the primary key, duplicates should not be allowed in the email field either. The email field is a unique key, and id is the primary key.
This relationship is represented in the table information as MUL (or "multiple") in the Key field:
mysql> describe subscribers;+-------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+----------------+
| id | int(11) | | PRI | NULL | auto_increment |
| email | varchar(150) | YES | MUL | NULL | |
+-------+--------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
Now that you have a table, you can create the form and script that place values in there.
Creating the Subscription Form
The subscription form will actually be an all-in-one form and script called manage.php, which will handle both subscribe and unsubscribe requests shows the code for manage.php, which uses a few user-defined functions to eliminate repetitious code.
Listing 18.1 Subscribe and
Unsubscribe with manage.php
1: <?php 2: //set up a couple of functions 3: function doDB() { 4: global $conn; 5: //connect to server and select database; you may need it 6: $conn = mysql_connect("localhost", "joeuser", "somepass") 7: or die(mysql_error()); 8: mysql_select_db("testDB",$conn) or die(mysql_error()); 9: } 10: 11: function emailChecker($email) { 12: global $conn, $check_result; 13: //check that email is not already in list 14: $check = "select id from subscribers where email = '$email'"; 15: $check_result = mysql_query($check,$conn) or die(mysql_error()); 16: } 17: 18: //determine if they need to see the form or not 19: if ($_POST[op] != "ds") { 20: //they do, so create form block 21: $display_block = " 22: <form method=POST action=\"$_SERVER[PHP_SELF]\"> 23: 24: <p><strong>Your E-Mail Address:</strong><br> 25: <input type=text name=\"email\" size=40 maxlength=150> 26: 27: <p><strong>Action:</strong><br> 28: <input type=radio name=\"action\" value=\"sub\" checked> subscribe 29: <input type=radio name=\"action\" value=\"unsub\"> unsubscribe 30: 31: <input type=\"hidden\" name=\"op\" value=\"ds\"> 32: 33: <p><input type=submit name=\"submit\" value=\"Submit Form\"></p> 34: </form>"; 35: 36: } else if (($_POST[op] == "ds") && ($_POST[action] == "sub")) { 37: //trying to subscribe; validate email address 38: if ($_POST[email] == "") { 39: header("Location: manage.php"); 40: exit; 41: } 42: //connect to database 43: doDB(); 44: //check that email is in list 45: emailChecker($_POST[email]); 46: 47: //get number of results and do action 48: if (mysql_num_rows($check_result) < 1) { 49: //add record 50: $sql = "insert into subscribers values('', '$_POST[email]')"; 51: $result = mysql_query($sql,$conn) or die(mysql_error()); 52: $display_block = "<P>Thanks for signing up!</P>"; 53: } else { 54: //print failure message 55: $display_block = "<P>You're already subscribed!</P>"; 56: } 57: } else if (($_POST[op] == "ds") && ($_POST[action] == "unsub")) { 58: //trying to unsubscribe; validate email address 59: if ($_POST[email] == "") { 60: header("Location: manage.php"); 61: exit; 62: } 63: //connect to database 64: doDB(); 65: //check that email is in list 66: emailChecker($_POST[email]); 67: 68: //get number of results and do action 69: if (mysql_num_rows($check_result) < 1) { 70: //print failure message 71: $display_block = "<P>Couldn't find your address!</P> 72: <P>No action was taken.</P>"; 73: } else { 74: //unsubscribe the address 75: $id = mysql_result($check_result, 0, "id"); 76: $sql = "delete from subscribers where id = '$id'"; 77: $result = mysql_query($sql,$conn) or die(mysql_error()); 78: $display_block = "<P>You're unsubscribed!</p>"; 79: } 80: } 81: ?> 82: <HTML> 83: <HEAD> 84: <TITLE>Subscribe/Unsubscribe</TITLE> 85: </HEAD> 86: <BODY> 87: <h1>Subscribe/Unsubscribe</h1> 88: <?php echo "$display_block"; ?> 89: </BODY>90: </HTML>
may be long, but it's not complicated. In fact, it could be longer, were it not for the user-defined functions at the top of the script. One of the reasons for creating your own functions is that you know you will be reusing a bit of code and don't want to continually retype it. Lines 3–9 set up the first function, doDB(), which is simply the database connection you've been making in your lessons for a while now. Lines 11–16 define a function called emailChecker(), which takes an input and returns an output—like most functions do. We'll look at this one in the context of the script, as we get to it.
If the value of $_POST[op] is indeed "ds", however, we need to do something. We have two possibilities: subscribe and unsubscribe. We determine which action to take by looking at the value of $_POST[action]—the radio button group.
In line 36, if $_POST[op] is "ds" and $_POST[action] is "sub", we know the user is trying to subscribe. To subscribe, he will need an email address, so we check for one in lines 38–41. If no address is present, the user is sent back to the form.
If an address is present, we call the doDB() function in line 43 to connect to the database because we need to perform a query (or two). In line 45, we call the second of our user-defined functions, emailChecker(). This function takes an input ($_POST[email]) and processes it. If we look back to lines 12–15, we see that the function is checking for an id value in the subscribers table that matches the value of the input. The function then returns the resultset, $check_result, for use within the larger script.
Note: the definition of global variables at the beginning of both user-defined functions in figures. These variables need to be shared with the entire script, and so are declared global.
Jump down to line 48 to see how $check_result is used: The number of records in $check_result is counted to determine whether the email address already exists in the table. If the number of rows is less than 1, the address is not in the list, and it can be added. The record is added and the response is stored in lines 50–52, and the failure message (if the address is already in the table) is stored in line 55. At that point, the script breaks out of the if...else construct, skips down to line 82, and proceeds to print the HTML. You'll test this functionality later.
The last combination of inputs occurs if the value of $_POST[op] is "ds" and $_POST[action] is "unsub". In this case, the user is trying to unsubscribe. To unsubscribe, he will need an email address, so we check for one in lines 59–61. If no address is present, the user is sent back to the form.
If an address is present, we call the doDB() function in line 64 to connect to the database. Then, in line 66, we call emailChecker(), which again will return the resultset, $check_result. The number of records in the resultset is counted in line 69, to determine whether the email address already exists in the table. If the number of rows is less than 1, the address is not in the list, and it cannot be unsubscribed. In this case, the response message is stored in lines 71–72. The user is unsubscribed(the record deleted) and the response is stored in lines 75–77, and the failure message (if the address is already in the table) is stored in line 78. At that point, the script breaks out of the if...else construct, skips down to line 82, and proceeds to print the HTML.
Below figures show the various results of the coded script, depending on the actions selected and the status of email addresses in the database
Developing the Mailing Mechanism
With the subscription mechanism in place, you can create a basic form interface for a script that will take the contents of your form and send it to every address in your subscribers table. This is another one of those all-in-one scripts, called sendmymail.php, and it is shown in above
Listing Send Mail to Your List of Subscribers
>Listing 18.2 Send Mail to
Your List of Subscribers
1: <?php 2: if ($_POST[op] != "send") { 3: //haven't seen the form, so show it 4: print " 5: <HTML> 6: <HEAD> 7: <TITLE>Send a Newsletter</TITLE> 8: </HEAD> 9: <BODY> 10: <h1>Send a Newsletter</h1> 11: <form method=\"post\" action=\"$_SERVER[PHP_SELF]\"> 12: <P><strong>Subject:</strong><br> 13: <input type=\"text\" name=\"subject\" size=30></p> 14: <P><strong>Mail Body:</strong><br> 15: <textarea name=\"message\" cols=50 rows=10 wrap=virtual></textarea> 16: <input type=\"hidden\" name=\"op\" value=\"send\"> 17: <p><input type=\"submit\" name=\"submit\" value=\"Send It\"></p> 18: </FORM> 19: </BODY> 20: </HTML>"; 21: 22: } else if ($_POST[op] == "send") { 23: //want to send form, so check for required fields 24: if (($_POST[subject] =="") || ($_POST[message] == "")) { 25: header("Location: sendmymail.php"); 26: exit; 27: } 28: 29: //connect to database 30: $conn = mysql_connect("localhost", "joeuser", "somepass") 31: or die(mysql_error()); 32: mysql_select_db("testDB",$conn) or die(mysql_error()); 33: 34: //get emails from subscribers list 35: $sql = "select email from subscribers"; 36: $result = mysql_query($sql,$conn) or die(mysql_error()); 37: 38: //create a From: mailheader 39: $headers = "From: Your Mailing List <you@yourdomain.com>\n"; 40: 41: //loop through results and send mail 42: while ($row = mysql_fetch_array($result)) { 43: set_time_limit(0); 44: $email = $row['email']; 45: mail("$email", stripslashes($_POST[subject]), 46: stripslashes($_POST[message]), $headers); 47: print "newsletter sent to: $email<br>"; 48: } 49: }The main logic of the script starts right there at line 2, where we determine whether the user has seen the form yet. If the value of $_POST[op] is not "send", we know the user has not submitted the form; therefore, we must show it to her. Lines 4–20 create the form for sending the newsletter, which uses $_SERVER[PHP_SELF] as the action (line 11), creates a text field called subject for the subject of the mail, and creates a textarea called message for the body of the mail to be sent. At this point, thescript breaks out of the if...else construct and the HTML is printed. The form is displayed as in 
If the value of $_POST[op] is indeed "send", however, we have to send the form to the recipients. Before we send, we must check for the two required items: $_POST[subject] and $_POST[message]. If either of these items is not present, the user is redirected to the form again.
If the required items are present, the script moves on to lines 30–32, which connect to the database. The query is issued in line 36, which grabs all the email addresses from the subscribers table. There is no order to these results, although you could throw an order by clause in there if you want to send them out in alphabetical order.
Line 39 creates a From: mail header, which is used inside the upcoming while loop, when mail is sent. This header ensures that the mail looks like it is from a person and not a machine. The while loop, which begins on line 42, extracts the email addresses from the resultset one at a time. On line 43, we use the set_time_limit() function to set the time limit to 0, or "no limit." Doing so allows the script to run for as long as it needs to.
Note: Because all the script is execute the mail() function numerous times, it does not take into account the queuing factors in actual mailing list software, which are designed to ease the burden on your outgoing mail server. Using set_time_limit() does not ease its burden; it just allows the script to continue to run when it might have timed out before.
In line 45, the mail is sent using the mail() function, inserting the values from the form where appropriate. Line 46 prints a message to the screen for you, to show who should have received the mail.You can see the outcome of the script.
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