PHP MySQL select array in array

Question

I have a field in my database that is an array ie: id_ingredients = "1,8,3,9,5,2,7,4"

I want to compare a variable that is also an array to give a result if any of the variable ids exist in the field ids.

I am trying to check to see if a product's ingredients contain any of the ingredients in the variable. If someone is allergic to nuts for example i want to selet all products that contain nuts of any kind. So i query my ingredients to get the id of any ingredient that has the word "nut" in its name. Then i need to get the products with any of the ingredient ids.

This is what I have...

$alg = $_POST['alg'];

mysql_select_db($database, $Products);
$query_availIngredients = "SELECT * FROM ingredients WHERE ingredient LIKE '%$alg%' ";
$availIngredients = mysql_query($query_availIngredients, $Products) or die(mysql_error());
$row_availIngredients = mysql_fetch_assoc($availIngredients);

$ingarray = array(); 

    do{
         $ingarray[] = $row_availIngredients['id'];

    } while ($row_availIngredients = mysql_fetch_assoc($availIngredients));

$alg = implode (',', $ingarray);


mysql_select_db($database, $Products);
$query_Products = "SELECT *FROM products  WHERE 
 id_ingredients LIKE '%$alg%' " ;
$Products = mysql_query($query_Products, $Products) or die(mysql_error());
$row_Products = mysql_fetch_assoc($Products);

Thank you in advance for your help.

Answer 1

Placing an array of IDs in a single database field isn't really a good idea and you lose some of the power a relational database gives you by designing your database this way.

Rather than storing an array of ingredient IDs in your product's table I would create a third table.

An example table schema would be like this:

Products
  id
  productName
  productDescription

Ingredients
  id
  ingredientName

ProductIngredients
  id
  id_Products
  id_Ingredients

Some sample data might look like:

Products
id           productName                            productDescription
1            Peanutbutter And Jelly Sandwich        Best sandwich ever

Ingredients
id           ingredientName
1            Peanutbutter
2            Jelly
3            Special sauce
4            Bread

ProductIngredients
id           id_Products             id_Ingredients
1            1                       1
2            1                       2
3            1                       4

You could then get a list of IDs of ingredients containing the word 'nut' like this:

SELECT id FROM Ingredients WHERE ingredientName LIKE '%nut%'

And a list of products containing ingredients which contain the word 'nuts' like this:

SELECT
  Products.productName
FROM
  Products
  LEFT JOIN ProductIngredients ON ProductIngredients.id_Products = Products.id
  LEFT JOIN Ingredients ON Ingredients.id = ProductIngredients.id_Ingredients
WHERE
  Ingredients.ingredientName LIKE '%nut%'

You could get a list of ingredients for a product like this:

SELECT
  Ingredients.ingredientName
FROM
  Ingredients
  LEFT JOIN ProductIngredients ON ProductIngredients.id_Ingredients = Ingredients.id
WHERE
  ProductIngredients.id_Products = 1

This would give you a list such as this:

• Peanutbutter
• Jelly
• Bread

Edit

This is is called a many-to-many relationship.