問題：2.Author ( Ano, Name, Age, Sex ) Book ( Bno , Title , Publisher )Write ( Ano , Bno , IsFirstAuthor )，（2）給定書名，如果此書的作者只有一人，則輸出此作者名字，否則返回 NULL（函數(shù)）代碼如下：Create function pangduan(@Title char(10)) returns char AsBegindeclare @anum int,@Ano char(10),@Name char(10)select @anum=count(*) from write,book where write.Bno=book.Bno and Title=@Titleif @anum=1beginselect @Ano=Ano from write,book where write.Bno=book.Bno and Title=@Titleselect @Name=Name from author where Ano=@Anoendelsebeginset @Name=nullendreturn @Name調(diào)用函數(shù)的時(shí)候，應(yīng)該返回作者名字的時(shí)候，返回了十個(gè)空格，應(yīng)該返回null的時(shí)候，返回了一個(gè)空格，end