如何从MySQL表正确获取结果

Question

This is my product table

and I want to get all product where product_sizes in (Xl, M)

I am trying into this code

SELECT `id`,`name`,`sell_price`,`product_sizes`,`product_colors`
FROM `view_product_listing` 
WHERE `product_sizes` in ('XL', 'M')

return to me productId 15 and 16 but I want to productId 4,14,15,16

Answer 1

You should seriously avoid storing the sizes as CSV (comma separated) data, see below for an alternative table design. As a workaround, we can use FIND_IN_SET :

SELECT id, name, sell_price, product_sizes, product_colors
FROM view_product_listing
WHERE FIND_IN_SET('M', product_sizes) > 0 OR FIND_IN_SET('XL', product_sizes) > 0;

But note that a much better database design would be to have a separate table for products, sizes, and colors: (colors omitted)

products
id | name                                 | sell_price |
4  | Women Maxi White Dress               | 550.00     |
14 | Women Maxi Blue Dress                | 700.00     |
15 | Women Fit and Flare Multicolor Dress | 750.00     |
16 | Floral Print Straight Kurta          | 699.00     |

sizes
product_id | product_size
4          | XL
4          | M
14         | XL
14         | XXL
14         | L
14         | M
15         | XL
16         | M

Now we can use a straightforward join to find all products, and their metadata, which have either the medium or XL size:

SELECT
    p.id,
    p.name,
    p.sell_price,
    s.product_size
FROM products p
INNER JOIN sizes s
    ON p.id = s.product_id
WHERE
    s.product_size IN ('M', 'XL');

Answer 2

You can use FIND_IN_SET like this,

Version 1:

SELECT `id`,`name`,`sell_price`,`product_sizes`,`product_colors`
FROM `view_product_listing` 
WHERE FIND_IN_SET('XL',product_sizes) OR FIND_IN_SET('M',product_sizes)

EDIT 1

There is one more approach to achieve this,

Version 2:

SELECT `id`,`name`,`sell_price`,`product_sizes`,`product_colors`
FROM `view_product_listing` 
WHERE CONCAT(',',product_sizes,',') REGEXP ",(XL|M),"

Source link for second version .

EDIT 2

You product_sizes is having spaces after commas, which is not the behaviour find_in_set is expecting. To trim all spaces from that column,

UPDATE `table` SET `product_sizes` = REPLACE(`product_sizes`, ' ', '')

And now run any version query you want to try, it will work.

Answer 3

use find_in_set()

SELECT `id`,`name`,`sell_price`,`product_sizes`,`product_colors`
FROM `view_product_listing` 
WHERE FIND_IN_SET(product_sizes,'XL,M') 

Answer 4

If you are only searching for one size you could use the built-in MySQL function FIND_IN_SET()

SELECT `id`,`name`,`sell_price`,`product_sizes`,`product_colors`
FROM `view_product_listing` 
WHERE FIND_IN_SET('XL', product_sizes)

However it only supports a single string (unless you add additional OR 's, but that quickly becomes tedious).

The best approach would be to restructure your database so that the product sizes of items are in a seperate table with a reference to the item table and a size table.

That way you don't have to update your queries whenever you want to introduce new sizes and it will improve performance for your query.

A word of warning,

Do not attempt a LIKE clause, because search for LIKE '%XL%' will also match XXL