Você pode usar um
UNION
, que removerá as duplicatas (enquanto UNION ALL
manterá as duplicatas) SELECT FirstUrlColumn AS url
FROM myTable
UNION
SELECT secondUrlColumn AS url
FROM myTable
UNION
, que removerá as duplicatas (enquanto UNION ALL
manterá as duplicatas) SELECT FirstUrlColumn AS url
FROM myTable
UNION
SELECT secondUrlColumn AS url
FROM myTable