异常:object references an unsaved transient instance
1、建表,很简单的3个字段。主键,name,外键指向自身idCREATETABLE`NewTable`(
`id`int(11)NOTNULLAUTO_INCREMENT,
`name`varchar(50)CHARACTERSETutf8COLLATEutf8_general_ciNULLDEFAULTNULL,
`category_id`int(11)NULLDEFAULTNULL,
PRIM