问题描述

我有一些看起来像这样的一对多规范化数据.

I have some one-many normalized data that looks like this.

a | x
a | y
a | z
b | i
b | j
b | k

什么查询会返回数据，使得多"方表示为 CSV 字符串?

What query will return the data such that the "many" side is represented as a CSV string?

a | x,y,z
b | i,j,k

推荐答案

Mark,

如果您使用的是 11gR2 版本，而谁不是 :-)，那么您可以使用 listagg

If you are on version 11gR2, and who isn't :-), then you can use listagg

SQL> create table t (col1,col2)
  2  as
  3  select 'a', 'x' from dual union all
  4  select 'a', 'y' from dual union all
  5  select 'a', 'z' from dual union all
  6  select 'b', 'i' from dual union all
  7  select 'b', 'j' from dual union all
  8  select 'b', 'k' from dual
  9  /

Tabel is aangemaakt.

SQL> select col1
  2       , listagg(col2,',') within group (order by col2) col2s
  3    from t
  4   group by col1
  5  /

COL1  COL2S
----- ----------
a     x,y,z
b     i,j,k

2 rijen zijn geselecteerd.

如果您的版本不是 11gR2，而是高于 10gR1，那么我建议为此使用模型子句，如下所示:http://rwijk.blogspot.com/2008/05/string-aggregation-with-model-clause.html

If your version is not 11gR2, but higher than 10gR1, then I recommend using the model clause for this, as written here: http://rwijk.blogspot.com/2008/05/string-aggregation-with-model-clause.html

如果低于 10，那么您可以在 rexem 指向 oracle-base 页面的链接中或在上述博文中指向 OTN 线程的链接中看到几种技术.

If lower than 10, then you can see several techniques in rexem's link to the oracle-base page, or in the link to the OTN-thread in the blogpost mentioned above.

问候，罗布.

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