find方法
db.collection_name.find();
查詢所有的結果:
select * from users;
db.users.find();
指定返回那些列(鍵):
select name, skills from users;
db.users.find({}, {'name' : 1, 'skills' : 1});
補充說明: 第一個{} 放where條件 第二個{} 指定那些列顯示和不顯示 (0表示不顯示 1表示顯示)
where條件:
1.簡單的等於:
select name, age, skills from users where name = 'hurry';
db.users.find({'name' : 'hurry'},{'name' : 1, 'age' : 1, 'skills' : 1});
2.使用and
select name, age, skills from users where name = 'hurry' and age = 18;
db.users.find({'name' : 'hurry', 'age' : 18},{'name' : 1, 'age' : 1, 'skills' : 1});
3.使用or
select name, age, skills from users where name = 'hurry' or age = 18;
db.users.find({ '$or' : [{'name' : 'hurry'}, {'age' : 18}] },{'name' : 1, 'age' : 1, 'skills' : 1});
4.<, <=, >, >= ($lt, $lte, $gt, $gte )
select * from users where age >= 20 and age <= 30;
db.users.find({'age' : {'$gte' : 20, '$lte' : 30}});
5.使用in, not in ($in, $nin)
select * from users where age in (10, 22, 26);
db.users.find({'age' : {'$in' : [10, 22, 26]}});
6.匹配null
select * from users where age is null;
db.users.find({'age' : null);
7.like (mongoDB 支援Regex)
select * from users where name like "%hurry%";
db.users.find({name:/hurry/});
select * from users where name like "hurry%";
db.users.find({name:/^hurry/});
8.使用distinct
select distinct (name) from users;
db.users.distinct('name');
9.使用count
select count(*) from users;
db.users.count();
10.數組查詢 (mongoDB自己特有的)
如果skills是 ['java','python']
db.users.find({'skills' : 'java'}); 該語句可以匹配成功
$all
db.users.find({'skills' : {'$all' : ['java','python']}}) skills中必須同時包含java 和 python
$size
db.users.find({'skills' : {'$size' : 2}}) 遺憾的是$size不能與$lt等組合使用
$slice
db.users.find({'skills' : {'$slice : [1,1]}})
兩個參數分別是位移量和返回的數量
11.查詢內嵌文檔
12.強大的$where查詢 db.foo.find();
{ "_id" : ObjectId("4e17ce0ac39f1afe0ba78ce4"), "a" : 1, "b" : 3, "c" : 10 }
{ "_id" : ObjectId("4e17ce13c39f1afe0ba78ce5"), "a" : 1, "b" : 6, "c" : 6 }
如果要查詢 b = c 的文檔怎麼辦。
> db.foo.find({"$where":function(){ for(var current in this){
for(var other in this){
if(current != other && this[current] == this[other]){
return true;
}
}
}
return false;
}});
{ "_id" : ObjectId("4e17ce13c39f1afe0ba78ce5"), "a" : 1, "b" : 6, "c" : 6 }
1 ) . 大於,小於,大於或等於,小於或等於
$gt:大於
$lt:小於
$gte:大於或等於
$lte:小於或等於
例子:
db.collection.find({ "field" : { $gt: value } } ); // greater than : field > value
db.collection.find({ "field" : { $lt: value } } ); // less than : field < value
db.collection.find({ "field" : { $gte: value } } ); // greater than or equal to : field >= value
db.collection.find({ "field" : { $lte: value } } ); // less than or equal to : field <= value
如查詢j大於3,小於4:
db.things.find({j : {$lt: 3}});
db.things.find({j : {$gte: 4}});
也可以合并在一條語句內:
db.collection.find({ "field" : { $gt: value1, $lt: value2 } } ); // value1 < field < value
2) 不等於 $ne
例子:
db.things.find( { x : { $ne : 3 } } );
3) in 和 not in ($in $nin)
文法:
db.collection.find( { "field" : { $in : array } } );
例子: