mongodb

作者: 小米或者黄大仙_fcb5 | 来源:发表于2018-10-16 11:07 被阅读0次

    1.db.users.find()
    select * from users
    2.db.users.find({"age" : 27})
    select * from users where age = 27
    3.db.users.find({"username" : "joe", "age" : 27})
    select * from users where username = "joe" and age = 27
    4.db.users.find({}, {"username" : 1, "email" : 1})
    select username, email from users
    5.db.users.find({}, {"username" : 1, "_id" : 0})
    // no case // 即时加上了列筛选,_id也会返回;必须显式的阻止_id返回
    6.db.users.find({"age" : {"gte" : 18, "lte" : 30}})
    select * from users where age >=18 and age <= 30 // lt(<)lte(<=) gt(>)gte(>=)
    7.db.users.find({"username" : {"ne" : "joe"}}) select * from users where username <> "joe" 8.db.users.find({"ticket_no" : {"in" : [725, 542, 390]}})
    select * from users where ticket_no in (725, 542, 390)
    9.db.users.find({"ticket_no" : {"nin" : [725, 542, 390]}}) select * from users where ticket_no not in (725, 542, 390) 10.db.users.find({"or" : [{"ticket_no" : 725}, {"winner" : true}]})
    select * form users where ticket_no = 725 or winner = true
    11.db.users.find({"id_num" : {"mod" : [5, 1]}}) select * from users where (id_num mod 5) = 1 12.db.users.find({"not": {"age" : 27}})
    select * from users where not (age = 27)
    13.db.users.find({"username" : {"in" : [null], "exists" : true}})
    select * from users where username is null
    // 如果直接通过find({"username" : null})进行查询,那么连带"没有username"的纪录一并筛选出来
    14.db.users.find({"name" : /joey?/i}) // 正则查询,value是符合PCRE的表达式
    15.db.food.find({fruit : {all : ["apple", "banana"]}}) // 对数组的查询, 字段fruit中,既包含"apple",又包含"banana"的纪录 16.db.food.find({"fruit.2" : "peach"}) // 对数组的查询, 字段fruit中,第3个(从0开始)元素是peach的纪录 17.db.food.find({"fruit" : {"size" : 3}})
    // 对数组的查询, 查询数组元素个数是3的记录,size前面无法和其他的操作符复合使用 18.db.users.findOne(criteria, {"comments" : {"slice" : 10}})
    // 对数组的查询,只返回数组comments中的前十条,还可以{"slice" : -10}, {"slice" : [23, 10]}; 分别返回最后10条,和中间10条
    19.db.people.find({"name.first" : "Joe", "name.last" : "Schmoe"}) // 嵌套查询
    20.db.blog.find({"comments" : {"elemMatch" : {"author" : "joe", "score" : {"gte" : 5}}}})
    // 嵌套查询,仅当嵌套的元素是数组时使用,
    21.db.foo.find({"where" : "this.x + this.y == 10"}) // 复杂的查询,where当然是非常方便的,但效率低下。对于复杂查询,考虑的顺序应当是 正则 -> MapReduce -> where 22.db.foo.find({"where" : "function() { return this.x + this.y == 10; }"})
    // $where可以支持javascript函数作为查询条件
    23.db.foo.find().sort({"x" : 1}).limit(1).skip(10);
    / 返回第(10, 11]条,按"x"进行排序; 三个limit的顺序是任意的,应该尽量避免skip中使用large-number
    24.db.user.find({"name":/ab/})
    select * from user where name like "%ab%"
    25.db.user.find({"name:/ABC\(v/})
    select * from user where name like "%ABC(v%"
    加双斜杠的原因是所查字段里面有括号,要转义一下
    26.db.user.find({"name":/^ABC\(v/})
    select * from user where name like "ABC(v%"

    相关文章

      网友评论

          本文标题:mongodb

          本文链接:https://www.haomeiwen.com/subject/jjgczftx.html