最近学习MongoDB数据库基本开发知识，发现MongoDB的排除查$ne类似于Oracle的not in 或者not exists，

但是$ne只能对字符串键值对起作用而对数字类型不行，举例如下：

示例数据：

	> dvd=({"Type":"DVD","Title":"Matrix,The","Released":1999,"Cast":["Keanu Reeeves","Carrie-Anne Moss","Laurence Fishburne","Hugo Weaving","Gloria Foster","Joe Pantoliano"]})

{

	"Type" : "DVD",

	"Title" : "Matrix,The",

	"Released" : 1999,

	"Cast" : [

	"Keanu Reeeves",

	"Carrie-Anne Moss",

	"Laurence Fishburne",

	"Hugo Weaving",

	"Gloria Foster",

	"Joe Pantoliano"

]

}

	> db.media.insert(dvd)

	WriteResult({ "nInserted" : 1 })

	> dvd=({"Type":"DVD","Title":"Blade Runner","Released":1982})

	{ "Type" : "DVD", "Title" : "Blade Runner", "Released" : 1982 }

	> db.media.insert(dvd)

	WriteResult({ "nInserted" : 1 })

	> dvd=({"Type":"DVD","Title":"Toy Story 3","Released":2010})

	{ "Type" : "DVD", "Title" : "Toy Story 3", "Released" : 2010 }

	> db.media.insert(dvd)

	WriteResult({ "nInserted" : 1 })

>

正常的字符串排除查询，以示例数据中Title键进行测试：

	> db.media.find({"Type":"DVD","Title":{$ne:"Blade Runner"}})

	{ "_id" : ObjectId("595af5ce39297105e4322fbd"), "Type" : "DVD", "Title" : "Matrix,The", "Released" : 1999, "Cast" : [ "Keanu Reeeves", "Carrie-Anne Moss", "Laurence Fishburne", "Hugo Weaving", "Gloria Foster", "Joe Pantoliano" ] }

	{ "_id" : ObjectId("595af63239297105e4322fbf"), "Type" : "DVD", "Title" : "Toy Story 3", "Released" : 2010 }

>

		对数字排除无效，以示例数据中Released键进行测试：
	
		> db.media.find({"Type":"DVD","Release":{$ne:"1999"}})
	
		{ "_id" : ObjectId("595af5ce39297105e4322fbd"), "Type" : "DVD", "Title" : "Matrix,The", "Released" : 1999, "Cast" : [ "Keanu Reeeves", "Carrie-Anne Moss", "Laurence Fishburne", "Hugo Weaving", "Gloria Foster", "Joe Pantoliano" ] }
	
		{ "_id" : ObjectId("595af61939297105e4322fbe"), "Type" : "DVD", "Title" : "Blade Runner", "Released" : 1982 }
	
		{ "_id" : ObjectId("595af63239297105e4322fbf"), "Type" : "DVD", "Title" : "Toy Story 3", "Released" : 2010 }
	
		>
	
		> db.media.find({"Type":"DVD","Release":{$ne:1999}})
	
		{ "_id" : ObjectId("595af5ce39297105e4322fbd"), "Type" : "DVD", "Title" : "Matrix,The", "Released" : 1999, "Cast" : [ "Keanu Reeeves", "Carrie-Anne Moss", "Laurence Fishburne", "Hugo Weaving", "Gloria Foster", "Joe Pantoliano" ] }
	
		{ "_id" : ObjectId("595af61939297105e4322fbe"), "Type" : "DVD", "Title" : "Blade Runner", "Released" : 1982 }
	
		{ "_id" : ObjectId("595af63239297105e4322fbf"), "Type" : "DVD", "Title" : "Toy Story 3", "Released" : 2010 }
	
		>
	
		实验结果：mongodb的$ne操作只能对字符串键值对发挥作用。
	
		本次实验的MongoDB数据库版本是：3.2.7
	
		操作系统是：Red Hat Enterprise Linux Server release 6.4 (Santiago)

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MongoDB的排除查询$ne缺陷

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