将关联表展平为多值列? [英] Flatten association table to multi-value column?

问题描述

我有一个表格，其中只有产品 ID 和类别 ID(产品可以属于多个类别).我怎样才能将类别 ID 拼合到一个产品列中，所以我以这个结束:

I have a table with just product ID's and category ID's (products can be in more than one category). How can I flatten the category ID's into a product column so I end us with this:

id | name | desc | categories
1 | test1 | lorem | 1,3,4,23
2 | test2 | ipsom | 4,6,24

这就像我需要循环到类别列的单独表中.我该怎么做，或者有更好的方法吗?

It is like I need to loop into a separate table for the categories column. How can I do this or is there a better way?

推荐答案

在 MSSQL 中没有内置的方法来做到这一点.

There's no in-built way to do it in MSSQL.

在 Microsoft SQL Server 2005 中模拟 group_concat MySQL 函数? 很好地描述了如何实施变通方法.

Simulating group_concat MySQL function in Microsoft SQL Server 2005? has a good description of how to go about implementing a workaround.

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