postgresql 如何在 Postgres/SQL 中获得两个整数的最小值/最大值？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/2936348/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to get min/max of two integers in Postgres/SQL?
提问by HRJ
How do I find the maximum (or minimum) of two integers in Postgres/SQL? One of the integers is not a column value.
如何在 Postgres/SQL 中找到两个整数的最大值（或最小值）？整数之一不是列值。
I will give an example scenario:
我将给出一个示例场景：
I would like to subtract an integer from a column (in all rows), but the result should not be less than zero. So, to begin with, I have:
我想从一列（在所有行中）减去一个整数，但结果不应小于零。所以，首先，我有：
UPDATE my_table
SET my_column = my_column - 10;
But this can make some of the values negative. What I would like (in pseudo code) is:
但这会使某些值变为负值。我想要的（伪代码）是：
UPDATE my_table
SET my_column = MAXIMUM(my_column - 10, 0);
回答by Mark Byers
Have a look at GREATEST and LEAST.
UPDATE my_table
SET my_column = GREATEST(my_column - 10, 0);
回答by Donnie
You want the inline sql case:
你想要内联 sql case：
set my_column = case when my_column - 10 > 0 then my_column - 10 else 0 end
max()is an aggregate function and gets the maximum of a row of a result set.
max()是一个聚合函数，获取结果集中一行的最大值。
Edit: oops, didn't know about greatestand leastin postgres. Use that instead.
编辑：哎呀，不知道greatest和least在 postgres 中。改用那个。
