sql - postgresql如何连接多个表以获得逗号分隔的输出

Question

我有下表:

• table1 id, user_id, first_name, last_name
• table2 id, user_id, company_name, first_name, last_name, partner_id
• 表 3 企业 ID、企业名称

我想创建将返回数据行的查询: user_id, (first_name last_name), (business_name, business_name ...) 当用户与多个企业相关联时，是这样的: 123、李四，业务 1，业务 2

当我使用以下查询时，我会得到一些重复的行:

SELECT table1.first_name, table1.last_name, table2.copmany_name,
       (case when concat(table1.first_name, table1.last_name) = '' then table2.company_name else concat_ws(' ', table1.first_name,table1.last_name) end) as name,
       table3.name as business_name
FROM table1
JOIN table2 ON table1.user_id = table2.user_id
JOIN table3 ON table2.partner_id = table3.id

这是该查询的示例:

123, John Doe, Business1
123, John Doe, Business2
125, Marie Bird, Business3

我想得到:

123, John Doe, Business1, Business2
125, Marie Bird, Business3

这可能吗？

谢谢

Answer 1

您可以使用 array_agg在 postgresql.Aggregate 函数中从一组输入值计算单个结果。:

SELECT table1.first_name, table1.last_name, table2.copmany_name,
       (case when concat(table1.first_name, table1.last_name) = '' then table2.company_name else concat_ws(' ', table1.first_name,table1.last_name) end) as name,
       array_agg(table3.name) as business_name
FROM table1
JOIN table2 ON table1.user_id = table2.user_id
JOIN table3 ON table2.partner_id = table3.id