[英]Get max and min from fields
我有兩個表:
First:
id | title
1 | aaa
2 | bbb
3 | ccc
Second:
id | first_id | one | two | three | four
1 | 1 | 3 | 1 | 4 | 6
2 | 2 | 4 | 4 | 1 | 2
3 | 3 | 1 | 2 | 3 | 4
我想展示一下:
id | title | min | max
1 | aaa | 1 | 6
2 | bbb | 1 | 4
3 | ccc | 1 | 4
SQL可能嗎? 怎么樣? :)
規范化數據庫 。 使用當前設置,這並非不可能,但絕對不建議這樣做。
-編輯-
如果必須的話,可以使用LEAST()和GREATEST()
-edit2-
SELECT
a.id,
a.title,
LEAST(b.one,b.two,b.three,b.four) min,
GREATEST(b.one,b.two,b.three,b.four) max
FROM first a
INNER JOIN second b ON a.id=b.first_id
閱讀湯姆的答案,這將是最好的選擇。
無論如何,可恥的是:
SELECT f.id, f.title
MIN(LEAST(s.one, s.two, s.three, s.four)) as min,
MAX(GREATEST(s.one, s.two, s.three, s.four)) as max
FROM First f
INNER JOIN Second s on f.id = s.first_id
GROUP BY f.id, f.title
如果Second不能有多個具有相同first_id的行,則可以刪除MIN和MAX(和Group by)。
您可以使用UNION
做到這一點。 試試這個:
SELECT a.id, a.title, MIN(b.c) `Min`, MAX(b.c) `Max`
FROM First a INNER JOIN
(
SELECT first_id, `one` c FROM `Second`
UNION
SELECT first_id, `two` c FROM `Second`
UNION
SELECT first_id, `three` c FROM `Second`
UNION
SELECT first_id, `four` c FROM `Second`
) b on a.id = b.First_ID
GROUP BY a.id
select first_id,F.title ,MIN(num) [min],MAX(num) [max] from (
select first_id,[one] [num]from [Second] union all
select first_id,[two] [num]from [Second] union all
select first_id,[three] [num]from [Second] union all
select first_id,[four] [num] from [Second] )[Second]
join [First] F
on Id=first_id
group by first_id,F.title
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