SQL查詢，對於表A中的每一行，應以逗號分隔結果的形式獲取多個行值（一列）

Question

下面，我描述這些表並解釋我要編寫的查詢，

訪問表

+--------------+------------------+--------+-------+-----------+
|   FIELD      |      TYPE        | NULL   | KEY   | DEFAULT   |
+--------------+------------------+--------+-------+-----------+
| VISIT_ID     | VARCHAR(200)     | NO     | UNI   | NULL      |
| PATIENT      | VARCHAR(45)      | NO     | PRI   | NULL      |
| DOCTOR       | VARCHAR(45)      | NO     | PRI   | NULL      |
| COMPLAINTS   | CLOB(2147483647) | YES    |       | NULL      |
| OBSERVATIONS | CLOB(2147483647) | YES    |       | NULL      |
| REPORTS      | VARCHAR(500)     | YES    |       | NULL      |
| START        | TIMESTAMP(23)    | NO     | PRI   | NULL      |
| END          | TIMESTAMP(23)    | NO     | PRI   | NULL      |
| CREATED_ON   | DATE(8)          | NO     | PRI   | NULL      |
| UPDATED_ON   | DATE(8)          | YES    |       | NULL      |
| STATUS       | VARCHAR(200)     | NO     | PRI   | NULL      |
| TYPE         | VARCHAR(200)     | YES    |       | NULL      |
| DESCRIPTION  | VARCHAR(200)     | NO     |       | NULL      |
+--------------+------------------+--------+-------+-----------+

和高亮表

+----------+------------------+--------+-------+-----------+
| FIELD    |      TYPE        | NULL   | KEY   | DEFAULT   |
+----------+------------------+--------+-------+-----------+
| VISIT_ID | VARCHAR(200)     | NO     |       | NULL      |
| MATTER   | CLOB(2147483647) | NO     |       | NULL      |
+----------+------------------+--------+-------+-----------+

現在我要查詢的是，對於訪問表中的每個VISIT，我想在Highlight表中獲取多個記錄。 我可以使用內部聯接，但是它給我重復的訪問記錄（請參見下面的SQL）

select "PUBLIC"."VISIT"."VISIT_ID", "PUBLIC"."VISIT"."DESCRIPTION", "PUBLIC"."VISIT"."START", "PUBLIC"."HIGHLIGHTS"."MATTER" from "PUBLIC"."VISIT", "PUBLIC"."HIGHLIGHTS" where "PUBLIC"."VISIT"."VISIT_ID" = "PUBLIC"."HIGHLIGHTS"."VISIT_ID" order by "PUBLIC"."VISIT"."START" asc

這將返回以下結果：

+------------------+-------------+-------------------------+-------------+
|     VISIT_ID     | DESCRIPTION |          START          |   MATTER    |
+------------------+-------------+-------------------------+-------------+
| 5178231763512765 | Head Ache   | 2014-05-07 23:08:10.383 | HIGH BP     |
| 5178231763512765 | Head Ache   | 2014-05-07 23:08:10.383 | SUGAR       |
| 5178231763512765 | Head Ache   | 2014-05-07 23:08:10.383 | BROKEN BONE |
+------------------+-------------+-------------------------+-------------+

但是我想要的是以下內容：

+------------------+-------------+-------------------------+---------------------------+
|     VISIT_ID     | DESCRIPTION |          START          |          MATTER           |
+------------------+-------------+-------------------------+---------------------------+
| 5178231763512765 | Head Ache   | 2014-05-07 23:08:10.383 | HIGH BP~SUGAR~BROKEN BONE |
+------------------+-------------+-------------------------+---------------------------+

一些可以幫助如何編寫查詢以獲取類似上面的數據？ 如果需要，“事項”可以是任何變量。

Answer 1

您可以使用group_concat聚合函數（在mysql和H2中提供）來完成此操作。 所以試試這個：

select "PUBLIC"."VISIT"."VISIT_ID"
, "PUBLIC"."VISIT"."DESCRIPTION"
, "PUBLIC"."VISIT"."START"
,group_concat( "PUBLIC"."HIGHLIGHTS"."MATTER" SEPERATROR ',') as MatterAggre
from "PUBLIC"."VISIT", "PUBLIC"."HIGHLIGHTS" 
where "PUBLIC"."VISIT"."VISIT_ID" = "PUBLIC"."HIGHLIGHTS"."VISIT_ID" 
group by "PUBLIC"."VISIT"."VISIT_ID", "PUBLIC"."VISIT"."DESCRIPTION", "PUBLIC"."VISIT"."START"
order by "PUBLIC"."VISIT"."START" asc