SQL Server 相当于 Oracle LEAST？
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SQL Server equivalent to Oracle LEAST?
提问by Jade
I've been looking for a good equivalent to the Oracle LEAST function.
我一直在寻找与 Oracle LEAST 函数相当的等效项。
I'm hoping to implement a user defined function that does about 10 fairly complex calculations, and takes the minimum value from each of those calculations.
我希望实现一个用户定义的函数，该函数执行大约 10 次相当复杂的计算，并从每个计算中获取最小值。
What I would do in Oracle is:
我会在 Oracle 中做的是：
SELECT LEAST
(
select expression1 from dual,
select expression2 from dual,
select expression3 from dual
) from dual
See http://www.techonthenet.com/oracle/functions/least.phpfor more on Oracle LEAST.
有关Oracle LEAST 的更多信息，请参见http://www.techonthenet.com/oracle/functions/least.php。
If expression1 returned 10, expression2 return 5, and expression3 reeturned 30, the whole expression would return 5.
如果表达式 1 返回 10，表达式 2 返回 5，表达式 3 返回 30，则整个表达式将返回 5。
Because this may be about 10-20 calculations, the CASE WHEN syntax is going to get unwieldy fast.
因为这可能需要大约 10-20 次计算，所以 CASE WHEN 语法很快就会变得笨拙。
Although the code will be more readable if we break it up more, I thought it would be more efficient to do it within one database query. Let me know I'm incorrect on that point, please!
尽管如果我们将代码分解得更多，代码将更具可读性，但我认为在一个数据库查询中执行它会更有效。请让我知道我在这一点上是不正确的！
I.e., is a stored procedure with 20 simple queries significantly slower than a stored procedure with one query that references a lot of tables all in one query.
即，是一个具有 20 个简单查询的存储过程，比具有一个查询的存储过程慢得多，该查询在一个查询中引用了很多表。
回答by afftee
mayby this query could help:
也许这个查询可以帮助：
SELECT min(c1)
from (
select expression1 as c1
union all
select expression2 as c1
union all
select expression3 as c1
)
回答by Stanislav Voynovski
The function Least() is applied horizontally in Oracle (on a row level), while Min() is applied vertically over a column. The example in the question required Min().
函数 Least() 在 Oracle 中水平应用（在行级别），而 Min() 垂直应用在列上。问题中的示例需要 Min()。
