Initialization of bean failed; nested exception is org.springframework.beans.factory.: 错误分析

mongo之查询

1，find命令初步使用。

查询某个集合中的文档，比如查询集合user中的文档命令如下：

db.user.find()

> db.user.find()

{ "_id" : ObjectId("50900a7fdc60973b77877536"), "name" : "zhlccna", "age" : 42 }

{ "_id" : ObjectId("50900a94dc60973b77877537"), "name" : "zhlccna1", "age" : 19 }

{ "_id" : ObjectId("50900aa5dc60973b77877538"), "name" : "zhlccna2", "age" : 1 }

{ "_id" : ObjectId("509010d7eb5b2c744c6b9247"), "name" : 20, "age" : "zhlccna" }

2,查询符文档中某个键值/数值 为特定的文档

db.user.find({"age" : 19})

> db.user.find({"age" : 19})

d" : ObjectId("50900a94dc60973b77877537"), "name" : "zhlccna1", "age" : 19 }

3,指定返回值

db.user.find({},{"age" : 1})

> db.user.find({},{"age" : 1})

{ "_id" : ObjectId("50900a7fdc60973b77877536"), "age" : 42 }

{ "_id" : ObjectId("50900a94dc60973b77877537"), "age" : 19 }

{ "_id" : ObjectId("50900aa5dc60973b77877538"), "age" : 1 }

{ "_id" : ObjectId("509010d7eb5b2c744c6b9247"), "age" : "zhlccna" }

返回user集合中所有文档的age字段

但是结果中会自动返回_id键值，如下代码可以去除返回信息的_id键值

db.user.find({},{"age" : 1 ,"_id" : 0})

> db.user.find({},{"age" : 1 ,"_id" : 0})

{ "age" : 42 }

{ "age" : 19 }

{ "age" : 1 }

{ "age" : "zhlccna" }

4,查询条件

$lt $lte $gt $gte $ne ,分别对应 > 、>= 、< 、<=、 =

年龄大于1小于42

db.user.find({"age" : {"$gt" : 1, "$lt" : 42}})

> db.user.find({"age"  :  {"$gt" : 1, "$lt" : 42}})

{ "_id" : ObjectId("50900a94dc60973b77877537"), "name" : "zhlccna1", "age" : 19 }

5、OR查询

db.user.find({"$or" : [{"name" : "zhlccna"}, {"age" : 1}]})

> db.user.find({"$or" : [{"name" : "zhlccna"}, {"age" : 1}]})

{ "_id" : ObjectId("50900a7fdc60973b77877536"), "name" : "zhlccna", "age" : 42 }

{ "_id" : ObjectId("50900aa5dc60973b77877538"), "name" : "zhlccna2", "age" : 1 }