[英]How to Compare Multiple Columns and Rows of a Table
我有一個大數據表,看起來像這樣
ID Marker Value1 Value2
================================
1 A 10 11
1 B 12 13
1 C 14 15
2 A 10 11
2 B 13 12
2 C
3 A 10 11
3 C 12 13
我想通過以下數據搜索此數據,這些數據是用戶輸入的而不是存儲在表中:
Marker Value1 Value2
==========================
A 10 11
B 12 13
C 14 14
結果應該是這樣的:
ID Marker Value1 Value2 Match?
==========================================
1 A 10 11 true
1 B 12 13 true
1 C 14 15 false
2 A 10 11 true
2 B 13 12 true
2 C false
3 A 10 11 true
3 C 12 13 false
最終,這是必要的(上表不是必需的,它應該證明這些值是如何產生的):
ID Matches Percent
========================
1 2 66%
2 2 66%
3 1 33%
我正在尋找最有前途的方法來使其在SQL(確切地說是PostgreSQL)中起作用。
我的想法:
我對這兩種方法都不滿意,因此提出了問題。 如何有效地比較兩個這樣的表?
您可以使用CTE預先計算匹配項。 然后,簡單的聚合即可解決問題。 假設您的參數是:
Marker Value1 Value2
==========================
m1 x1 y1
m2 x2 y2
m3 x3 y3
你可以做:
with x as (
select
id,
case when
marker = :m1 and (value1 = :x1 and value2 = :y1 or value1 = :y1 and value2 = :x1)
or marker = :m2 and (value1 = :x2 and value2 = :y2 or value1 = :y2 and value2 = :x2)
or marker = :m3 and (value1 = :x3 and value2 = :y3 or value1 = :y3 and value2 = :x3)
then 1 else 0 end as matches
from t
)
select
id,
sum(matches) as matches,
100.0 * sum(matches) / count(*) as percent
from x
group by id
嘗試這個:
CREATE TABLE #Temp
(
Marker nvarchar(50),
Value1 nvarchar(50),
Value2 nvarchar(50)
)
INSERT INTO #Temp Values ('A', '10', '11')
INSERT INTO #Temp Values ('B', '12', '13')
INSERT INTO #Temp Values ('C', '14', '14')
SELECT m.Id, m.Marker, m.Value1, m.Value2,
(Select
CASE
WHEN COUNT(*) = 0 THEN 'False'
WHEN COUNT(*) <> 0 THEN 'True'
END
FROM #Temp t
WHERE t.Marker = m.Marker and t.Value1 = m.Value1 and t.Value2 = m.Value2) as Matches
FROM [Test].[dbo].[Markers] m
ORDER BY Matches DESC
Drop TABLE #Temp
如果這正是您想要的,我會嘗試解決它的第二部分。
可以使用公用表表達式中的VALUES子句提供用戶輸入,然后可以在與實際表的左聯接中使用該用戶輸入。
with user_input (marker, value1, value2) as (
values
('A', 10, 11),
('B', 12, 13),
('C', 14, 14)
)
select d.id,
count(*) filter (where (d.marker, d.value1, d.value2) is not distinct from (u.marker, u.value1, u.value2)),
100 * count(*) filter (where (d.marker, d.value1, d.value2) is not distinct from (u.marker, u.value1, u.value2)) / cast(count(*) as numeric) as pct
from data d
left join user_input u on (d.marker, d.value1, d.value2) = (u.marker, u.value1, u.value2)
group by d.id
order by d.id;
返回:
id | count | pct
---+-------+------
1 | 2 | 66.67
2 | 2 | 66.67
3 | 1 | 50.00
在線示例: https : //rextester.com/OBOOD9042
編輯
如果值的順序無關緊要(因此(12,13)被認為與(13,12)相同),則比較會變得更加復雜。
with user_input (marker, value1, value2) as (
values
('A', 10, 11),
('B', 12, 13),
('C', 14, 14)
)
select d.id,
count(*) filter (where (d.marker, least(d.value1, d.value2), greatest(d.value1, d.value2)) is not distinct from (u.marker, least(u.value1, u.value2), greatest(u.value1, u.value2)))
from data d
left join user_input u on (d.marker, least(d.value1, d.value2), greatest(d.value1, d.value2)) = (u.marker, least(u.value1, u.value2), greatest(u.value1, u.value2))
group by d.id
order by d.id;
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