In what movie did Doris Day first sing, “Que Sera, Sera”?

'The Man Who Knew Too Much' is a 1956 American suspense thriller film directed and produced by Alfred Hitchcock, starring James Stewart and Doris Day. The film is Hitchcock's second film using this same title following his own 1934 film of the same name featuring a significantly different plot and script.

Hitchcock's frequent composer, Bernard Herrmann, wrote the "background" film score; however, the performance of Arthur Benjamin's Storm Clouds Cantata, conducted by Herrmann, is used as source music for the climax of the film.

In addition, Doris Day's character is a well-known, now retired, professional singer. At two points in the film, she sings the Livingston and Evans song "Que Sera, Sera (Whatever Will Be, Will Be)" which won the 1956 Best Song Oscar under the alternate title "Whatever Will Be, Will Be (Que Sera, Sera)". The song reached number two on the US pop charts and number one in the UK.