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）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調用函數的時候，應該返回作者名字的時候，返回了十個空格，應該返回null的時候，返回了一個空格，end