zoukankan      html  css  js  c++  java
  • MongoDB 正则表达式

    示例

    MongoDB 使用 $regex 操作符来设置匹配字符串的正则表达式。

    > db.col.find()
    { "_id" : ObjectId("56c6bbef64799370c0ef358a"), "x" : "hello world", "tags" : [ "a", "b" ] }
    { "_id" : ObjectId("56c6bbfe64799370c0ef358b"), "x" : "hi world", "tags" : [ "b" ] }
    { "_id" : ObjectId("56c6bc9e64799370c0ef358c"), "x" : "nothing" }
    > db.col.find({x:/world/}) { "_id" : ObjectId("56c6bbfe64799370c0ef358b"), "x" : "hi world", "tags" : [ "b" ] } { "_id" : ObjectId("56c6bbef64799370c0ef358a"), "x" : "hello world", "tags" : [ "a", "b" ] }
    > db.col.find({x:{$regex:"world"}}) { "_id" : ObjectId("56c6bbfe64799370c0ef358b"), "x" : "hi world", "tags" : [ "b" ] } { "_id" : ObjectId("56c6bbef64799370c0ef358a"), "x" : "hello world", "tags" : [ "a", "b" ] }

    上面后两种操作是等价的。

    不区分大小写

    > db.col.find({x:{$regex:"world", $options:"$i"}})
    { "_id" : ObjectId("56c6bd9964799370c0ef358d"), "x" : "hihi WORLD" }
    { "_id" : ObjectId("56c6bbfe64799370c0ef358b"), "x" : "hi world", "tags" : [ "b" ] }
    { "_id" : ObjectId("56c6bbef64799370c0ef358a"), "x" : "hello world", "tags" : [ "a", "b" ] }

    or

    > db.col.find({x:/world/i})
    { "_id" : ObjectId("56c6bd9964799370c0ef358d"), "x" : "hihi WORLD" }
    { "_id" : ObjectId("56c6bbfe64799370c0ef358b"), "x" : "hi world", "tags" : [ "b" ] }
    { "_id" : ObjectId("56c6bbef64799370c0ef358a"), "x" : "hello world", "tags" : [ "a", "b" ] }

    数组使用正则表达式

    > db.col.find({tags:/b/})
    { "_id" : ObjectId("56c6bbef64799370c0ef358a"), "x" : "hello world", "tags" : [ "a", "b" ] }
    { "_id" : ObjectId("56c6bbfe64799370c0ef358b"), "x" : "hi world", "tags" : [ "b" ] }
    { "_id" : ObjectId("56c6bedf64799370c0ef358e"), "tags" : [ "abc", "m" ] }

    可见数组中包含字符‘b’的都找出来了(包括“abc”)。

    正则中包含变量

    需要用eval将组合的字符串进行转换

    > v="world"
    world
    
    > db.col.find({x:eval("/" + v + "/i")})
    { "_id" : ObjectId("56c6bd9964799370c0ef358d"), "x" : "hihi WORLD" }
    { "_id" : ObjectId("56c6bbfe64799370c0ef358b"), "x" : "hi world", "tags" : [ "b" ] }
    { "_id" : ObjectId("56c6bbef64799370c0ef358a"), "x" : "hello world", "tags" : [ "a", "b" ] }
  • 相关阅读:
    实例讲解如何在Delphi中动态创建dxBarManager内容
    SqlServer中创建Oracle连接服务器
    Delphi中的四舍五入函数
    Delphi中的四舍五入函数
    垃圾回收内存管理
    列表生成式
    列表函数&方法
    python切片
    python函数def
    Python 控制流、列表生成式
  • 原文地址:https://www.cnblogs.com/kaituorensheng/p/5201225.html
Copyright © 2011-2022 走看看