Question

Is it possible build an array of SQL commands to query the DB? What I have is three tables, each have columns with amounts due. Would like to select anything that is due and display on screen so it can be invoiced (preferably in a table) and each row with it’s respective customers dues.

I can select everything that is due using UNION ALL between the three tables, however I cant figure out how to list them by ID in the table row.

Below is what I have so far. At this pace I’ll have to run each query separately and list them in three separate lists. Suggestions?

      <table>
        <tr>
            <th> ID</th>
            <th> Cost 1</th>
            <th> Cost 2</th>
            <th> Cost 3</th>
        </tr>

      <?php 
    $list1 = "SELECT ID, Cost FROM Table1 WHERE Invoiced IS NULL;";
    //$list2 = "SELECT ID, Price2 FROM Table2 WHERE Expiration BETWEEN '$curDate' AND '$maxDate';";
    //$list3 = "SELECT ID, Price3 FROM Table3 WHERE Expiration BETWEEN '$curDate' AND '$maxDate'";

    $result = mysql_query($list1, $link) or die(mysql_error());

    $num_rows = mysql_num_rows($result);
    $num_fields = mysql_num_fields($result);

    for ($i=0; $i<$num_rows; $i++) {
        for ($j=0; $j<$num_fields; $j++) {
            $invoice[$i][mysql_fieldname($result,$j)] = mysql_result($result,$i,mysql_field_name($result,$j));
            }
        }

    //eventually the order it should be listed on screen
    for($i=0; $i<count($invoice); $i++) {
        echo "<tr><td>".$invoice[$i]["ID"]."</td>
        <td>".$invoice[$i]["Cost"]."</td>
        <td>".$invoice[$i]["Price2"]."</td>
        <td>".$invoice[$i]["Price3"]."</td></tr>";
    }

      ?>
      </table>

Edit after comment:

Query being passed and returning syntax error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'all LEFT JOIN table1 ON all.ID = table1.ID LEFT JOIN t' at line 7:

    $query = "
    SELECT all.ID, table1.Cost1, table2.Price2, tabl3.Price3
    FROM 
        (SELECT ID, Cost1 FROM table1 WHERE Invoiced IS NULL
            UNION
        SELECT ID, Price2 FROM table2 WHERE Expiration BETWEEN '$curDate' AND '$maxDate'
            UNION
        SELECT ID, Price3 FROM table3 WHERE Expiration BETWEEN '$curDate' AND '$maxDate') AS all
    LEFT JOIN table1 ON all.ID = table1.ID
    LEFT JOIN table2 ON all.ID = table2.ID
    LEFT JOIN table3 ON all.ID = table3.ID
    ";

Answer 1

From the table header you have created above which places the three Cost columns in a single row by ID, you seem to imply that you want to to JOIN the three tables together on their ID. I am using a LEFT JOIN here, to be sure that all rows from Table1 are present, even if there is no corresponding row in either of the other two tables.

SELECT
  Table1.ID,
  Table1.Cost as Cost1,
  Table2.Price2 AS Cost2,
  Table3.Price3 AS Cost3
FROM
  Table1 
  LEFT JOIN Table2 ON Table1.ID = Table2.ID
  LEFT JOIN Table3 ON Table1.ID = Table3.ID
WHERE 
  Table1.Invoiced IS NULL
  AND Table2.Expiration BETWEEN '$curDate' AND '$maxDate'
  AND Table3.Expiration BETWEEN '$curDate' AND '$maxDate'

Update after comments:

In the case that Table2 may have an ID not held in Table1 or Table3, for example (where Table1.ID can’t be considered authoritative), you can get the total set of DISTINCT ID from all 3 tables via a UNION and use that to join against:

SELECT
  allID.ID,
  Table1.Cost1,
  Table2.Price2 AS Cost2,
  Table2.Price3 AS Cost3
FROM
  /* Subquery gets a distinct set of IDs from all tables via UNION 
     so the outer query has a complete list to join against the other tables */
  (
    SELECT ID FROM Table1
    UNION SELECT ID FROM Table2
    UNION SELECT ID FROM Table3
  ) allID
  LEFT JOIN Table1 ON allID.ID = Table1.ID
  LEFT JOIN Table2 ON allID.ID = Table2.ID
  LEFT JOIN Table3 ON allID.ID = Table3.ID
/* Sorry, forgot the WHERE clause here */
WHERE
  Table1.Invoiced IS NULL
  AND Table2.Expiration BETWEEN '$curDate' AND '$maxDate'
  AND Table3.Expiration BETWEEN '$curDate' AND '$maxDate'

Note that the existence of three tables with nearly identical column structures in a one-to-one relationship probably implies a design problem. You might consider combining these into a single table.

A further note about the PHP:

In PHP, we almost never use an incremental for loop for iteration as you would in C/C++. Instead, we typically make use of a foreach or when fetching rows from a query, a while loop.

// Fetch in a while loop
$invoice = array();
// $result is your query resource as you already have it...
while ($row = mysql_fetch_assoc($result)) {
  // Accumulate rows into $invoice array
  $invoice[] = $row;
}
// Then loop over the array:
foreach ($invoice as $inv) {
  echo "<tr>
    <td>{$inv['ID']}</td>
    <td>{$inv['Cost1']}</td>
    <td>{$inv['Cost2']}</td>
    <td>{$inv['Cost3']}</td>
  </tr>"; 
}

Final update:

Yes, the WHERE clause will restrict for all conditions met. If you need to limit them individually, you must do so in subqueries which are then joined together, using the same UNION subquery to get the distinct set of ID

SELECT
  allID.ID,
  T1.Cost1,
  T2.Price2 AS Cost2,
  T3.Price3 AS Cost3
FROM
  (
    SELECT ID FROM Table1
    UNION SELECT ID FROM Table2
    UNION SELECT ID FROM Table3
  ) allID
  LEFT JOIN (SELECT ID, Cost AS Cost1 FROM Table1 WHERE Invoiced IS NULL) T1 ON allID.ID = T1.ID
  LEFT JOIN (SELECT ID, Price2 AS Cost2 FROM Table2 WHERE Expiration BETWEEN '$curDate' AND '$maxDate') T2 ON allID.ID = T2.ID
  LEFT JOIN (SELECT ID, Price3 AS Cost3 FROM Table3 WHERE Expiration BETWEEN '$curDate' AND '$maxDate') T3 ON allID.ID = T3.ID