在Postgres查询结果中获取表名

Question

我想在查询结果中获取表名.我试图做的查询涉及多个表.这就是为什么我试图获得一个带有结果的列,该结果将指示从哪个表中获取数据.这是我正在使用的代码

(SELECT DISTINCT column_1 as keywords from table_1) 
UNION ALL
(SELECT DISTINCT column_2 as keywords from table_2)

Answer 1

用这个:

SELECT DISTINCT column_1 AS keywords, 'table_1' AS tablename
FROM table_1
UNION ALL
SELECT DISTINCT column_2 AS keywords, 'table_2' AS tablename
FROM table_2

它tablename向结果集添加一列,其中包含原始表名.