如何将多列的列不同值作为具有相应列名的数组获取？

Question

我正在尝试将多列的不同值作为数组获取。我试过使用函数 array_agg

    Color  |  State     |  Item
=================================
    Red    |  New York  |  Balloon
    Pink   |  Virginia  |  Table
    Black  |  Utah      |  Table

我想要一个table作为

    Column_name  | Options
===============================
    Color        | [Red,Pink,Black]
    State        | [New York,Virginia,Utah]
    Item         | [Balloon,Table]

我试过这个：

select (array_agg(distinct "Color"))  from sample_table
union 
select (array_agg(distinct "State")) from sample_table
union 
select (array_agg(distinct "Item")) from sample_table
union

我卡在如何获取相应的列名了..!

Answer 1

您只需像这样添加 column_names：

SELECT 'Color' AS column_name, array_agg(distinct "Color") AS options from sample_table
UNION
SELECT 'State' AS column_name, array_agg(distinct "State") AS options from sample_table
UNION
SELECT 'Item' AS column_name, array_agg(distinct "Item") AS options from sample_table

工作Fiddle

如何将多列的列不同值作为具有相应列名的数组获取？

How to get column distinct values of multiple columns as array with corresponding column name?

sql

postgresql-9.1