尝试使用PHP和MySQL（内部联接）返回记录集

Question

I am new to PHP/MySQL to please bear with me. I am trying to have PHP write a table which returns a list of records from a join table. The SQL statement works perfectly when I run the query but I do not know how to write the function properly.

SQL statement which works:

---

SELECT members.nick_name, assets.asset_desc, shares.asset_cost, shares.percent_owner
          FROM 
            (shares INNER JOIN assets
            ON shares.asset_ID = assets.asset_ID)
            INNER JOIN members
            ON shares.member_ID = members.member_ID
            WHERE shares.member_ID = $member_ID"

---

My functions:

---

function get_shares_by_member($member_ID) {
global $db;
$query = "SELECT members.nick_name, assets.asset_desc, shares.asset_cost, shares.percent_owner
          FROM 
            (shares INNER JOIN assets
            ON shares.asset_ID = assets.asset_ID)
            INNER JOIN members
            ON shares.member_ID = members.member_ID
            WHERE shares.member_ID = $member_ID";
$share_result = $db->query($query);
$share_result = $share_result->fetch();
return $share_result;
}

function get_shares() {
global $db;
$query = "SELECT * FROM shares";
$share = $db->query($query);
$shares_table = $share->fetch();
return $share;
}

---

My action:

if (isset($_POST['action'])) {
$action = $_POST['action'];
} else if (isset($_GET['action'])) {
$action = $_GET['action'];
} else {
$action = 'list_shares';
}

if ($action == 'list_shares') {
if (!isset($member_ID)) {
    $member_ID = 0;
}
$shares = get_shares_by_member($member_ID);
$share = get_shares();
}

---

Here is my table:

---

<table>
<tr>
    <th>Nick Name</th>
    <th>Asset Description</th>
    <th>Asset Cost</th>
    <th class="right">% Ownership<th>
    <th>&nbsp;</th>
</tr>
<?php foreach ($shares_table as $share) : ?>
<tr>
    <td><?php echo $share['nick_name']; ?></td>
    <td><?php echo $share['asset_desc']; ?></td>
    <td><?php echo $share['asset_cost']; ?></td>
    <td class="right"><?php echo $share['percent_owner']; ?></td>
    <td>&nbsp;</td>
</tr>
<?php endforeach; ?>
</table>

---

I know this is a lot to ask but I've been struggling with this for the past 3 days. Any help will be much appreciated! If anyone needs help with AD/Exchange, I'd be happy to share my knowledge in that area!

Thanks!!

Answer 1

From what I can see on here, this will produce a blank table with however many rows are returned for a number of reasons:

• None of the columns returned by the get_shares_by_member function are share_ID or asset_ID, so those columns won't be filled in.
• You are referencing percent_owner from $shares which, assuming is an array as you are using it in a 'foreach' loop, will need an index to reference it, or it should otherwise be $share['percent_owner']
• The percent_owner field will be put in the 'asset cost' column at present as there is no blank cell produced to move it to the '% ownership' column where it would seem logical to have it.

Based on what you have posted so far, the following should suit your needs:

<table>
    <tr>
        <th>Nick Name</th>
        <th>Asset Description</th>
        <th>Asset Cost</th>
        <th class="right">% Ownership<th>
        <th>&nbsp;</th>
    </tr>
    <?php foreach ($shares as $share) : ?>
    <tr>
        <td><?php echo $share['nick_name']; ?></td>
        <td><?php echo $share['asset_desc']; ?></td>
        <td><?php echo $share['asset_cost']; ?></td>
        <td class="right"><?php echo $shares['percent_owner']; ?></td>
        <td>&nbsp;</td>
    </tr>
    <?php endforeach; ?>
</table>

I would recommend changing either the $share variable in the foreach, or the $share which is being set by get_shares(). Personally speaking, I would change the latter from

$share = get_shares();

to something like:

$shares_table = get_shares();

as it is essentially containing all of the information from the shares table, assuming the database abstraction layer function fetch() returns all results.

There could also be an issue when you are doing:

$share = $db->query($query);
$share = $share->fetch();

Going from different database abstraction layers I have seen, I would expect fetch() to be done as (using your variables)

$share = $db->fetch();

If the fetch() is requiring a result to be passed into it, then I would expect the code to look similar to:

$share_result = $db->query($query);
$share = $db->fetch($share_result);

Answer 2

a few points:

1. are you sure your query does not return any errors? If there are errors, that might cause fetch() to fail
2. what DB class are you using? I would suggest that you please check that there is a fetch() function and what parameters does it accept? For example, the fetch() may be invoked like $share_result->fetch() or $db->fetch() or $db->fetch($share_result) etc.
3. I might be wrong but it seems that the fetch() might be always returning the first row from the resultset. Perhaps you might need to do fetch() in a loop for reading all results

You may as well try using the default PHP functions. Here is a code snippet that explains how you may rewrite your functions using PHP's default mysql() library:

mysql_connect('your host', 'your user', 'your password'); function get_shares_by_member($member_ID) {
    $output = Array();
    $query = "SELECT members.nick_name, assets.asset_desc, shares.asset_cost, shares.percent_owner
              FROM 
                (shares INNER JOIN assets ON shares.asset_ID = assets.asset_ID)
                INNER JOIN members ON shares.member_ID = members.member_ID
                WHERE shares.member_ID = $member_ID";
    $share_result = mysql_query($query);
    while ($row = mysql_fetch_assoc($share_result)) {
        $output[] = $row;
    }
    return $output;
}

function get_shares() {
    $output = Array();
    $query = "SELECT * FROM shares";
    $share = mysql_query($query);
    while ($row = mysql_fetch_assoc($share)) {
        $output[] = $row;
    }
    return $output; 
}

Hope the above helps. Please feel free to let me know if there is anything that is not clear.