CREATE TABLE table_23649244_2 (release_date VARCHAR, artist_1 VARCHAR)

If artist 1 is Wolfgang Gartner, what is the release date?
SELECT release_date FROM table_23649244_2 WHERE artist_1 = "Wolfgang Gartner"
SELECT "release_date" FROM "table_23649244_2" WHERE "Wolfgang Gartner" = "artist_1"