Displaying MySQL records with PHP

To query a MariaDB - MariaDB is a fork of MySQL - database using PHP, code similar to that shown below can be used. In this exmple, the account used to query the database is johndoe with a password of ThePassword. The database is named Acme and contains a table named Accounts.

<?php

$con = mysql_connect("localhost","johndoe","ThePassword");

if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

mysql_select_db("Acme", $con);

$accounts = mysql_query("SELECT * FROM Accounts");

?>

The above code, which is included on a webpage, selects all of the records in the table. The code below calls a function that displays each selected record, i.e., all records, since all records were selected above.

<?php

// Display accounts
while($account = mysql_fetch_array($accounts))
{
   displayAccount($account);
}

?>

The code below, which is included near the top of the web page, provides a function that displays individual records from the table.

<?php
function displayAccount($account) {

   echo "<tr>\n";
   echo "<td><a href=\"" . $account['URL'] . "\">" .
         $account['ID'] . "</a></td>";
   echo "<td>" . $account['Description'] . "</td>";
   echo "<td>" . $account['Category'] . "</td>";
   echo "<td>" . $account['Type'] . "</td>";
   echo "<td>" . $account['Note'] . "</td>\n";
   echo "</tr>\n\n";

}
?>

The following fields are displayed for each record: ID, Description, Category, Type, and Note. The ID is displayed as a clickable link that leads to a webpage stored as a URL in the table column named URL. Where a double quote shuold appear in the output HTML, e.g., <a href="someurl", the double quote is preceded by a backslash, which serves as an escape character, i.e., it prevents PHP from assuming the double quote is part of the PHP code, but, instead, instructs it to treat it as just any other character without any special meaning.

Supposing that there are times when I don't want to see every entry in the table, but only the record corresponding to a specific ID, I could use http://example.com/acme/accounts.php to have the code above executed to display all records in the Accounts table in the Acme database, but specify a parameter with the URL when I only want to display an entry corresponding to a specific ID with http://example.com/acme/accounts.php?id=acctid where I would substitute a specific account's id in place of acctid, e.g., http://example.com/acme/accounts.php?id=A014VEONP7. Above I have the line:

$accounts = mysql_query("SELECT * FROM Accounts");

Instead of just that line, I could have the following code on the page:

if (isset($_GET["account"]))
{
   $chosen = $_GET["id"];
   $accounts = mysql_query("SELECT * FROM Accounts WHERE ID = '{$chosen}'");
}
else
{
   $accounts = mysql_query("SELECT * FROM Accounts");
}

The PHP code checks to see if the parameter account has been passed with if (isset($_GET["account"])). If it has been passed in the URL and is thus set, then only records where the account ID matches the value passed in the URL with ?id= will be displayed, since the list of selected records passed to the displayAccts function will contain only the record, or records, with the specified ID. This is done by setting a variable named chosen to the value of the id parameter and then using WHERE ID = followed by that variable name enclosed withing single quotes and braces.

If I wanted to display that record, or records, differently than when I display all records on the webpage, I could create a separate function to handle the display and call it, instead of the displayAccts function.

 

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