我不知道如何编写一个sql查询以显示所需的信息

Question

I've gotten my database set up for my website and I'm a little baffled on how I should write the SQL query to display the information how I want it.

Here's an image of how my database is setup and an example of how I want to display it:

Here's the SQL query I wrote to get the information (Im open to writing a better solution)

SELECT * FROM drinks_category, drinks_lookup, drinks
WHERE drinks.drink_id = drinks_lookup.drink_id
AND drinks_lookup.drinks_category_id = drinks_category.drinks_category_id

This gets me all the info but I'm not sure how to write the output to get it to show how i want.

Answer 1

One solution is to order by category:

SELECT * 
FROM drinks_category, drinks_lookup, drinks 
WHERE drinks.drink_id = drinks_lookup.drink_id 
AND drinks_lookup.drinks_category_id = drinks_category.drinks_category_id
ORDER BY drinks_category.drink_category_title

With that, you can loop in PHP, and output a new header whenever a new category appears. Something like this:

<?php
$last_category = 0;
foreach($data as $row) {
    if($row['drinks_category_id'] != $last_category) {
        echo '<h1>' . $row['drink_category_title'] . '</h1>';
    }
    echo '<div>' . $row['drinks_name'] . '</div>';
    $last_category = $row['drinks_category_id'];
}
?>

You should probably use nested html lists instead of the markup above, but this should get you started.

Answer 2

Since you use PHP, the best way to do this is to use an outer-inner-query loop:

Outer query: SELECT * FROM drings_category , then loop:

• Display drink_category_title
• Use drink_category_id as $ID for SELECT drinks.drink_name FROM drinks INNER JOIN drinks_lookup ON drinks.drink_id=drinks_lookup.drink_id WHERE drinks_lookup.drink_category_id=$ID
• Loop and display drinks

Answer 3

Hideously over complicated way to do it in a single sql statement for 3 fixed columns, coping with up to 1000 drinks in each category.

SELECT DrinkCategory1Subselect.drink_name AS 'Drink Category Title', DrinkCategory2Subselect.drink_name AS 'Drink Category Title 2', DrinkCategory3Subselect.drink_name AS 'Drink Category Title 3'
FROM (SELECT a.i+b.i*10+c.1*100 AS aCounter
FROM (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) a,
(SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) b,
(SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) c) Deriv1
INNER JOIN (SELECT  c.drink_name, 
    @Counter := @Counter + 1 AS aCounter
FROM drinks_category a
INNER JOIN drinks_lookup b ON a.drink_category_id = b.drink_category_id
INNER JOIN drinks c ON b.drink_id = c.drink_id
CROSS JOIN (SELECT @Counter:=0) NothingUseful
WHERE a.drink_category_id = 1
ORDER BY c.drink_id) DrinkCategory1Subselect
ON DrinkCategory1Subselect.aCounter = Deriv1.aCounter
INNER JOIN (SELECT  c.drink_name, 
    @Counter := @Counter + 1 AS aCounter
FROM drinks_category a
INNER JOIN drinks_lookup b ON a.drink_category_id = b.drink_category_id
INNER JOIN drinks c ON b.drink_id = c.drink_id
CROSS JOIN (SELECT @Counter:=0) NothingUseful
WHERE a.drink_category_id = 2
ORDER BY c.drink_id) DrinkCategory2Subselect
ON DrinkCategory2Subselect.aCounter = Deriv1.aCounter
INNER JOIN (SELECT  c.drink_name, 
    @Counter := @Counter + 1 AS aCounter
FROM drinks_category a
INNER JOIN drinks_lookup b ON a.drink_category_id = b.drink_category_id
INNER JOIN drinks c ON b.drink_id = c.drink_id
CROSS JOIN (SELECT @Counter:=0) NothingUseful
WHERE a.drink_category_id = 3
ORDER BY c.drink_id) DrinkCategory3Subselect
ON DrinkCategory3Subselect.aCounter = Deriv1.aCounter
WHERE DrinkCategory1Subselect.drink_name IS NOT NULL
OR DrinkCategory2Subselect.drink_name IS NOT NULL
OR DrinkCategory3Subselect.drink_name IS NOT NULL
ORDER BY Deriv1.aCounter

Not tested. Better to do the formatting in php, but was bored