oracle 如何在oracle中使用COALESCE合并两行数据
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how to use COALESCE in oracle to combine data from two rows
提问by Omnipresent
I have the following query which is inside a loop and is breaking
我有以下查询，它在循环内并且正在中断
SELECT COALESCE(v_user_grade || ', ', '') || user_grade
INTO v_user_grade
FROM EXPIRATION_HISTORY__2
WHERE hist_id = v_test;
So basically in each iteration of the loop we get a new value for v_test. In some cases this query would return multiple rows. that is when it is breaking.
所以基本上在循环的每次迭代中，我们都会为 v_test 获得一个新值。在某些情况下，此查询将返回多行。那是它破裂的时候。
What I want is:
我想要的是：
Data in EXPIRATION_HISTORY__2:
EXPIRATION_HISTORY__2 中的数据：
hist_id user_grade
301 ADMIN
302 ADMIN
302 USER
so now based on the above data. ...in the end of the iteration where v_test = 302. I would want v_user_gradeto contain (ADMIN, USER)
所以现在基于上述数据。...在迭代结束的地方v_test = 302。我想v_user_grade包含 ( ADMIN, USER)
回答by pyrocumulus
I think the following link describes exactly that what you want:
我认为以下链接准确描述了您想要的内容：
http://www.oracle-base.com/articles/10g/StringAggregationTechniques.php
http://www.oracle-base.com/articles/10g/StringAggregationTechniques.php
String Aggregation Techniques
On occasion it is necessary to aggregate data from a number of rows into a single row, giving a list of data associated with a specific value.
字符串聚合技术
有时，需要将多行中的数据聚合到一行中，从而给出与特定值相关联的数据列表。
I'm not an Oracle expert; but there are multiple solutions, depending on your DB enviroment.
我不是 Oracle 专家；但是有多种解决方案，具体取决于您的数据库环境。
