数据库仅从链接列表中吐出特定ID的行数据，而不是数据库中的所有行

Question

I have a PHP page that spits out the ID # and the Last Name from a table in a database.

I want to be able to click on the ID #, have it go to a new page, and view the rows info for that specfic ID # only.

Here is some code from my print.php page where it lists out the ID # and the Last Name which works great.

ID # = m_id

Last Name = m2_2

$db = new mysqli('localhost', 'username', 'password', 'name');

if($db->connect_errno > 0)
{ 
die('Unable to connect to database [' . $db->connect_error . ']'); 
}

$sql = "SELECT * FROM `test_gina` ORDER BY m_id DESC";

if(!$result = $db->query($sql)){
die('There was an error running the query [' . $db->error . ']');
}

while($row = $result->fetch_assoc()){

if($row['m_id'] =="x"){echo " ";}else{ echo '<a href="id.php">'; echo $row['m_id'];}echo '</a>';

if($row['m2_2'] =="x"){echo " ";}else{echo $row['m2_2'];}echo '<br>';

When it goes to the id.php, it shows ALL the rows from the table in the database.

I am not that expierenced in databases, so I know I am doing it wrong, but how do I "connect" the 2 pages to have id.php only show the information for that specfic ID #?

Here is some of my code from my id.php page.

$db = new mysqli('localhost', 'username', 'password', 'name');

if($db->connect_errno > 0)
{ 
die('Unable to connect to database [' . $db->connect_error . ']'); 
}

$sql = "SELECT * FROM `test_gina` ORDER BY m_id DESC";

if(!$result = $db->query($sql)){
die('There was an error running the query [' . $db->error . ']');
}

while($row = $result->fetch_assoc()){

if($row['m_id'] =="x"){echo " ";}else{echo '<strong>ID #:</strong>'; echo $row['m_id'];}echo '</br>';
echo "";if($row['m_P'] =="x"){echo " ";}else
{
switch($row['m_P'])
{
case "35310":
echo "<strong>Persons living/Household:</strong> 1"; 
break;
}

Any help would be appreciated greatly!!!

Answer 1

You should really look into writing "clean" codes. That being said, in your "print.php" replace

echo '<a href="id.php">'; echo $row['m_id'];}echo '</a>'

with

echo '<a href="id.php?id='. $row['m_id']. '">'. $row['m_id']. '</a>'

Notice I'm using concatenation, rather than multiple echo statements.

Briefly put, the "?" and what follows it in the href attribute of the <a> tag is what is called a query string.

Then, in your "id.php" file, you get hold of the query string using the GET super global, like below:

$id = $_GET['id'];

your query string should then look like this:

$sql = "SELECT * FROM `test_gina` WHERE m_id = $id ORDER BY m_id DESC";