最近學習MongoDB資料庫基本開發知識，發現MongoDB的排除查$ne類似於Oracle的not in 或者not exists，

但是$ne只能對字串鍵值對起作用而對數字型別不行，舉例如下：

示例資料：

> 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 })

>

正常的字串排除查詢，以示例資料中Title鍵進行測試：

> 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 }

>

對數字排除無效，以示例資料中Released鍵進行測試：

> 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 }

>

實驗結果：mongodb的$ne操作只能對字串鍵值對發揮作用。

本次實驗的MongoDB資料庫版本是：3.2.7

作業系統是：Red Hat Enterprise Linux Server release 6.4 (Santiago)

MongoDB的排除查詢$ne缺陷

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