使用 PHP 从 MySQL DB 中订购项目列表中的标题

Question

Hoping someone has an idea of a good way to query/handle these headings...

As an example, if you have a recipe, it might look like this: (with headings and ingredients)

---

Salad

• Fresh Lettuce
• Chopped carrots
• Fresh Strawberries

Dressing

• Vinegar
• Sugar
• Cinnamon

Garnish

• Sliced Almonds

---

In the MySQL database, I'll be storing this data in a recipe table. So this recipe might look like this:

 +----+---------------+-----------------+--------------------+---------------------+-----------+---------+-----------+---------+-----------+---------+ | id | ingredient_1 | ingredient_2 | ingredient_3 | ingredient_4 etc... | heading_a | h_a_pos | heading_b | h_b_pos | heading_c | h_c_pos | +----+---------------+-----------------+--------------------+---------------------+-----------+---------+-----------+---------+-----------+---------+ | 1 | Fresh Lettuce | Chopped carrots | Fresh Strawberries | Vinegar | Salad | 1 | Dressing | 4 | Garnish | 7 | +----+---------------+-----------------+--------------------+---------------------+-----------+---------+-----------+---------+-----------+---------+

Where the ingredients are all stored together, and the headings are stored together. (Different recipes will need different headings and in different positions in relation to ingredients.) Here the heading position (h_a_pos, etc.) indicate the ingredient # to list the heading before.

When it comes to querying this to display it, if I run a simple SQL query:

 SELECT * FROM recipes WHERE id = 1;

That will just return me a list of everything. Here's an SQL Fiddle: http://sqlfiddle.com/#!9/942d8a3/1/0

With PHP, I could then take the results, and put it into an array. And I'm sure there's some way I could sort them, but I'm drawing a blank...

 $response = []; // blank array $sql_retrieve = $con->prepare("SELECT * FROM recipes WHERE id = 1"); $sql_retrieve->execute(); $result = $sql_retrieve->get_result(); if($result->num_rows>0){ while($row=$result->fetch_assoc()){ $response[] = $row; } // end of while } // end of num_rows print_r($response); // display response pre-sorting // sort array -- not working usort($response, function($a, $b) { return $a['h_a_pos'] <=> $b['h_b_pos']; }); // would need something to order it in relation to the ingredients... echo '<br /><br />'; print_r($response); // display response post-sorting

I can change the database structure, but would prefer to keep this within one table if at all possible. (I realize some of the ingredients may not be normalized, but I'm not listing the amounts, etc. in this example either.)

Anyone have any ideas on how to store the headings? I basically just need to know that it's supposed to be a heading (so it can be formatted appropriately), what the text should be, and before which ingredient number to display it. (I'd never be querying off the headings, so if this would be better stored serialized, that might be an option...)

Answer 1

What you've got there is not normal . You will run into troubles if, for example, you decide you want a complex recipe with more ingredients than columns, or more ingredient headings than columns. The important lesson to take away is that databases are not spreadsheets.

Here's something closer to the database structure that you want:

CREATE TABLE categories (id SERIAL, name VARCHAR(32));
CREATE TABLE ingredients (id SERIAL, category_id BIGINT UNSIGNED NOT NULL, name VARCHAR(32));
CREATE TABLE recipes (id SERIAL, name VARCHAR(32));
CREATE TABLE ingredients_recipes (recipe_id BIGINT UNSIGNED NOT NULL, ingredient_id BIGINT UNSIGNED NOT NULL);

Obviously, you'd want some foreign key constraints in there as well to enforce links between tables, but we'll skip that here. Populate it with your ingredients:

INSERT INTO categories VALUES (1, 'Salad'), (2, 'Dressing'), (3, 'Garnish');
INSERT INTO ingredients VALUES (1, 1, 'Fresh Lettuce'), (2, 1, 'Chopped Carrots'), (3, 1, 'Strawberries'), (4, 2, 'Balsamic Vinegar'), (5, 2, 'Olive Oil'), (6, 3, 'Sliced Almonds');
INSERT INTO recipes VALUES (1, 'My Salad');
INSERT INTO ingredients_recipes VALUES (1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (1, 6);

Now, the full recipe can be pulled using simple joins:

SELECT r.name AS recipe, c.name AS category, i.name AS ingredient
FROM ingredients i
LEFT JOIN categories c ON (i.category_id = c.id)
LEFT JOIN ingredients_recipes ON (ingredient_id = i.id)
LEFT JOIN recipes r ON (recipe_id = r.id)
WHERE r.id = ?
ORDER BY c.id ASC

Here's a fiddle to illustrate this: http://sqlfiddle.com/#!9/aecbbd/1

(Note the order of the "headings" is going to have to be something defined separately, at the time they're created. In this case I've just sorted by ID.)

Now, in your PHP you can easily execute this query and group the ingredients by category:

$stmt = $con->prepare($query);
$stmt->bind_param("i", $recipe_id);
$stmt->execute();
while ($row = $stmt->fetch_assoc()) {
    $name = $row["recipe"];
    $ingredient_types[$row["category"]][] = $row["ingredient"];
}

And during display, simply loop through the arrays:

<h1>How to make <?= $name ?></h1>
<?php foreach($ingredient_types as $category=>$ingredients): ?>
    <h2><?= $category ?></h2>
    <ul>
    <?php foreach ($ingredients as $ingredient): ?>
        <li><?= $ingredient ?></li>
    <?php endforeach ?>
    </ul>
<?php endforeach ?>

Your question mentioned quantities, these would be stored in the pivot table ingredients_recipes as an additional column and could easily be pulled into the SELECT clause.