! Exercise 7.5.4: Write the following as triggers. In each case, disallow or undo the modification if it does not satisfy the stated constraint. The problems are based on our running movie example: Movies (title, year, length , genre, studioName , producerC#) StarsIn(movieTitle, movieYear, starName) MovieStar (name, address, gender, birthdate) MovieExec (name, address, cert#, netWorth) Studio (name, address, presC4) You may assume that the desired condition holds before any change to the database is attempted. Also, prefer to modify the database, even if it means inserting tuples with NULL or default values, rather than rejecting the attempted modification. a) Assure that at all times, any star appearing in StarsIn also appears in MovieStar. b) Assure that at all times every movie executive appears as either a studio president, a producer of a movie, or both. c) Assure that every movie has at least one male and one female star