CREATE TABLE table_19794 ("Year" FLOAT, "Mens singles" TEXT, "Womens singles" TEXT, "Mens doubles" TEXT, "Womens doubles" TEXT, "Mixed doubles" TEXT)

who is the the mens doubles with mens singles being j rgen koch and womens singles being sabine ploner
SELECT "Mens doubles" FROM table_19794 WHERE "Mens singles" = 'Jürgen Koch' AND "Womens singles" = 'Sabine Ploner'
SELECT "Mens doubles" FROM "table_19794" WHERE "Mens singles" = 'Jürgen Koch' AND "Womens singles" = 'Sabine Ploner'