SQL字段作为其他字段的总和 [英] SQL field as sum of other fields
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问题描述
这与查询无关,我想知道的是,是否有可能在一个列中显示一个字段作为其他字段的总和.有点像Excel.
This is not query related, what I would like to know is if it's possible to have a field in a column being displayed as a sum of other fields. A bit like Excel does.
作为一个例子,我有两个表:
As an example, I have two tables:
食谱
nrecepie integer
name varchar(255)
time integer
和另一个
说明
nintrucion integer
nrecepie integer
time integer
所以,基本上,因为一个食谱有n条指令,我想要
So, basically as a recipe has n instructions I would like that
recipes.time = sum(intructions.time)
这可以在创建表脚本中完成吗?如果可以,怎么办?
Is this possible to be done in create table script?? if so, how?
推荐答案
您可以使用视图:
CREATE VIEW recipes_with_time AS
SELECT nrecepie, name, SUM(Instructions.time) AS total_time
FROM Recepies
JOIN Instructions USING (nrecepie)
GROUP BY Recepies.nrecepie
如果您真的想在真实表中包含这些数据,则必须使用触发器.
If you really want to have that data in the real table, you must use a trigger.
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