Re: UNION not working... why?

Oh great. Thanks a lot.

But now, I have another problem in this context. If I use text in the
SELECT statement (so, that the final output gives me the name of the
selected variables, plus the year and the value) than I get this
error message: ERROR:  failed to find conversion function from
"unknown" to text

If I just use one of the SELECTs, it works fine. But as soon as I use
the UNION ALL and add the second SELECT, the error message appears.

What am I doing wrong? Thanks for any hints!


> SELECT *
>    FROM (SELECT  'pop_density' AS name, d.year_start, d.value
>                    FROM emissions_so2_total_rivm AS d
>                               LEFT JOIN
>                               countries AS c ON c.id = d.id_country
>                  WHERE ((c.iso_2_code = 'CH') OR (c.iso_3_code =
> 'CH'))
>                  ORDER BY d.year_start DESC
>                  LIMIT 1) c1
> UNION ALL
> SELECT *
>    FROM (SELECT  'gdp' AS name, d.year_start, d.value
>                    FROM emissions_so2_total_rivm AS d
>                               LEFT JOIN
>                               countries AS c ON c.id = d.id_country
>                  WHERE ((c.iso_2_code = 'CH') OR (c.iso_3_code =
> 'CH'))
>                  ORDER BY d.year_start DESC
>                  LIMIT 1) c2