PostgreSQL-合并多个查询的结果行

Question

I am having trouble adding two columns together which are from the same table.column, with two different values.

How do I add the following two queries together to give two new columns with each their own value;

SELECT
    ... more columns ...
    components.description,
FROM
    ...
WHERE
    graphiccards.id = systems.id AND
    components.id = graphiccards.component_id;

SELECT
    components.description
FROM
    ...
WHERE
    components.id = mainboards.component_id AND
    mainboards.id = systems.mainboard_id

I would like these two results to be on the same row in two different columns.

https://gyazo.com/de8100b645d6e0ccad3d1ec664907246

Answer 1

You may wish to look at the UNION operator

select
  components.description
  stuff as second_column
from mytable where conditions

union

select
  components.description
  stuff2 as second_column
from mytable2 where conditions2

You just need to make sure you have the same nr of columns with the same name.