如何通过SQL将表中的垂直字段转换为水平结果 [英] how to transform vertical fields in a table to horizontal result by SQL

问题描述

我有一个这样的表:

create table t1 {
  person_id int,
  item_name varchar(30),
  item_value varchar(100)
};

假设person_id + item_name是组合键，现在我在表t1中有一些数据(5条记录)，如下所示:

Suppose person_id+item_name is the composite key, now I have some data (5 records) in table t1 as below:

person_id ====item_name ====== item_value
   1          'NAME'           'john'
   1          'GENDER'         'M'
   1          'DOB'            '1970/02/01'
   1          'M_PHONE'        '1234567890'
   1          'ADDRESS'        'Some Addresses unknown'

现在，我想使用SQL(或组合存储过程/函数或其他方法)来查询上述结果(1个结果集)成为:

Now I want to use SQL (or combing store procedure/function or whatever) to query the above result (1 result set) become:

NAME==GENDER==DOB========M_PHONE=======ADDRESS===============
1     M       1970/02/01 1234567890    Some Addresses unknown

我该怎么办? 谢谢您的帮助.

How should I do ? Thank you for your help.

推荐答案

无论使用哪种数据库，都将尝试实现的概念称为数据透视表".

Regardless of the database you are using, the concept of what you are trying to achieve is called "Pivot Table".

这是mysql的示例: http://en.wikibooks.org/wiki/MySQL/Pivot_table

Here's an example for mysql: http://en.wikibooks.org/wiki/MySQL/Pivot_table

某些数据库具有内置功能，请参见下面的链接.

Some databases have builtin features for that, see the links below.

SQLServer: http://msdn.microsoft.com/de-de/library/ms177410.aspx

SQLServer: http://msdn.microsoft.com/de-de/library/ms177410.aspx

Oracle: http://www.dba-oracle.com/t_pivot_examples.htm

您始终可以手动创建枢轴.只需选择结果集中的所有聚合，然后从该结果集中选择即可.请注意，在您的情况下，可以使用concat将所有名称放入一列(我认为这是mysql中的group_concat)，因为您不知道有多少名称与person_id相关.

You can always create a pivot by hand. Just select all the aggregations in a result set and then select from that result set. Note, in your case, you can put all the names into one column using concat (i think that's group_concat in mysql), since you cannot know how many names are related to a person_id.

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