SQL

Question

我有两个 table（轮播和 carousel_images）

轮播 table

id	small_img_1	small_img_2	large_img_1	large_img_2	img_cta_1	img_cta_2
75	101	102	103	104	cta_1	cta_2
76	201	202	203	204	xxx	xxx

carousel_images table

id	url	alt_tag
101	http_101	text_101
102	http_102	text_102
103	http_103	text_103
104	http_104	text_104

预期结果我想return以下结果。选择构建旋转木马所需的所有图像，其中 carousel.id == 1.

img_id	small_img	small_img_url	small_img_alt	large_img	large_img_url	large_img_alt	img_cta
1	101	http_101	text_101	103	http_103	text_103	cta_1
2	102	http_102	text_102	104	http_104	text_104	cta_2

问题 - 这就是我已经走了多远。我无法在我的结果中获得 large_img_1 和 large_img_2 的结果。

img_id	small_img	small_img_url	small_img_alt	img_cta
1	101	http_101	text_101	cta_1
2	102	http_102	text_102	cta_2

这是我目前的查询。

SELECT
    [img_id],
    [small_img],
    [large_img] [img_cta],
    [carousel_images].[url] AS 'small_img_url',
    [carousel_images].[alt_tag] AS 'small_img_alt'
FROM
    [dbo].[carousels] CROSS APPLY(

        VALUES
            (1, [small_img_1], [img_cta_1]),
            (2, [small_img_2], [img_cta_2])
    ) V(img_id, small_img, img_cta)
LEFT OUTER JOIN [carousel_images] ON [small_img] = [carousel_images].id
WHERE
    [carousel_images] = 75;

有人可以帮忙吗？我已经卡了好几天了。

它也是一个遗留系统，所以这就是为什么 table 结构是这样的。不幸的是我不能改变它:(

Answer 1

你快到了。

您需要将 large_img 添加到 CROSS APPLY。并加入 carousel_images 两次。一次用于 small_img 一次用于 large_img

SELECT
    v.[img_id],
    v.[small_img],
    s.[url]       AS small_img_url,
    s.[alt_tag]   AS small_img_alt,
    v.[large_img],
    l.[url]       AS large_img_url,
    l.[alt_tag]   AS large_img_alt,
    v.[img_cta]
FROM
    [dbo].[carousels] c
    CROSS APPLY
    (    
        VALUES
            (1, [small_img_1], [large_img_1], [img_cta_1]),
            (2, [small_img_2], [large_img_2], [img_cta_2])
    ) v (img_id, small_img, large_img, img_cta)
    LEFT OUTER JOIN [dbo].[carousel_images] s ON v.[small_img] = s.id
    LEFT OUTER JOIN [dbo].[carousel_images] l ON v.[large_img] = l.id

SQL - 如何在查询中使用 "CROSS APPLY"

SQL - How To Use "CROSS APPLY" In Query

sql-server

cross-apply