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[英]Oracle SQL: Update a table with data from another columns of the same table
[英]Update columns with date from the same Table sql
我有這個表結構
id | value
---|----------
1 | 0.2
2 | 0.3
3 | 0.5
4 | 0.25
5 | 0.37
6 | 0.56
7 |
8 |
9 |
現在我想用id = 2到5之間的值來更新最后3個元素的值,我這樣做是因為聽起來很簡單
UPDATE table AS z0
SET value = z1.value
FROM table as z1
WHERE z1.id BETWEEN 2 AND 5
AND z0.id BETWEEn 7 AND 9
但是結果是這樣的,只是取范圍(id = 2)中的第一個元素的值
id | value
---|----------
1 | 0.2
2 | 0.3
3 | 0.5
4 | 0.25
5 | 0.37
6 | 0.56
7 | 0.3
8 | 0.3
9 | 0.3
這樣行嗎?
update table
set value = (select value
from table t2
where id between 2 and 5
order by random()
limit 1
)
where value is null;
las,上面的方法行不通(盡管我認為應該如此)。 問題在於子查詢僅被執行一次。 此版本可以正常工作:
update table t
set value = (select value
from table t2
where id between 2 and 5 and t2.id <> t.id
order by random()
limit 1
)
where value is null;
相關子句阻止只運行一次查詢的優化。 這是一個SQL Fiddle,它演示了邏輯。
你可以用這個
UPDATE table AS z0
SET value = z1.value
FROM table as z1
WHERE z1.id = (z0.id - 4)
AND z0.id BETWEEn 7 AND 9
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