Question: Name the became consort for marriage of 4 April 1721
SQL: SELECT "Became Consort" FROM "2-12418234-5" WHERE "Marriage" = '4 April 1721';

Question: Name the birth of the person that has a spouse of Frederick IV and became consort of 4 April 1721
SQL: SELECT "Birth" FROM "2-12418234-5" WHERE "Spouse" = 'Frederick IV' AND "Became Consort" = '4 April 1721';

Question: Name the became consort for ceased to be consort of 4 April 1588 husband's death
SQL: SELECT "Became Consort" FROM "2-12418234-5" WHERE "Ceased to be Consort" = '4 April 1588 husband''s death';

Question: Name the marriage of the person who is married for Christian VIII
SQL: SELECT "Marriage" FROM "2-12418234-5" WHERE "Spouse" = 'Christian VIII';