如何更改表中数据的值？ [英] How do I change the value of data in table?

问题描述

每当我将aantal更改为0时，由于某种原因它会变回5。

有人知道为什么吗？

i想要为aantal填充一个数字然后乘以prijs。

everytime when i change aantal to 0 it changes back to 5 for some reason.
does someone know why?
i want to fill a number for aantal and then multiply it with "prijs".

bierid aantal  prijs
1	5	2
2	0	2
NULL	NULL	NULL

CREATE TABLE [dbo].[Bier] (
    [BierId]             INT IDENTITY (1, 1) NOT NULL,
    [Aantal_consumpties] INT NULL ,
    [Prijs]              INT NOT NULL,
    PRIMARY KEY CLUSTERED ([BierId] ASC)

我尝试过：



选择总和（Aantal_consumpties * Prijs）AS prijsbier FROM Bier;

What I have tried:

"select sum(Aantal_consumpties * Prijs) AS prijsbier FROM Bier";

推荐答案

你不做改变价值

You do not change the value by doing

select sum(Aantal_consumpties * Prijs) AS prijsbier FROM Bier

您需要的是更新：

What you need is an UPDATE:

UPDATE Bier SET Aantal_consumpties = 5;
select sum(Aantal_consumpties * Prijs) AS prijsbier FROM Bier;

你真的需要在这里度过一段时间 [click] [ ^ ]。这是一个相当友好的环境，您可以边做边学。



只要学习如何进行基本的SQL查询，就会更容易，特别是从长远来看。

You really need to spend some time here [click][^]. This is a rather friendly environment where you can learn-by-doing.

It's much easier, especially in the long run, to just learn how to do basic SQL queries.

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