问题描述
我希望从在 Oracle 中返回多行的查询中返回带有逗号分隔值列表的单行，实质上是将返回的行展平为单行.
I'm hoping to return a single row with a comma separated list of values from a query that returns multiple rows in Oracle, essentially flattening the returned rows into a single row.
在 PostgreSQL 中，这可以使用数组和 array_to_string 函数来实现，如下所示:
In PostgreSQL this can be achieved using the array and array_to_string functions like this:
给定表人":
id | name
---------
1 | bob
2 | alice
3 | jon
SQL:
select array_to_string(array(select name from people), ',') as names;
将返回:
names
-------------
bob,alice,jon
如何在 Oracle 9i 中获得相同的结果?
How would I achieve the same result in Oracle 9i?
谢谢，
马特
推荐答案
Tim Hall 拥有 Oracle 中的字符串聚合技术.
Tim Hall has the definitive collection of string aggregation techniques in Oracle.
如果您坚持使用 9i，我个人的偏好是定义一个自定义聚合(该页面上有 string_agg 的实现)，这样您就可以
If you're stuck on 9i, my personal preference would be to define a custom aggregate (there is an implementation of string_agg on that page) such that you would have
SELECT string_agg( name )
FROM people
但是你必须定义一个新的 STRING_AGG 函数.如果您需要避免创建新对象，还有其他方法，但在 9i 中它们会比 PostgreSQL 语法更混乱.
But you have to define a new STRING_AGG function. If you need to avoid creating new objects, there are other approaches but in 9i they're going to be messier than the PostgreSQL syntax.
这篇关于相当于 Oracle 9i 中的 PostgreSQL array()/array_to_string() 函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！