class Book {
String title
Date releaseDate
String author
}countBy*
用途
使用域类的属性查询匹配记录的数量的动态方法
示例
给定域类Book
以下这些均有可能
def c = Book.countByTitle("The Shining")
c = Book.countByTitleAndAuthor("The Sum of All Fears", "Tom Clancy")
c = Book.countByReleaseDateBetween(firstDate, new Date())
c = Book.countByReleaseDateGreaterThanEquals(firstDate)
c = Book.countByTitleLike("%Hobbit%")
c = Book.countByTitleNotEqual("Harry Potter")
c = Book.countByReleaseDateIsNull()
c = Book.countByReleaseDateIsNotNull()