一、聚集集合查询
1、查询所有记录
db.userInfo.find();
相当于:select* from userInfo;
默认每页显示20条记录,当显示不下的情况下,可以用it迭代命令查询下一页数据。注意:键入it命令不能带“;”
但是你可以设置每页显示数据的大小,用DBQuery.shellBatchSize= 50;这样每页就显示50条记录了。
2、查询去掉后的当前聚集集合中的某列的重复数据
db.userInfo.distinct("name");
会过滤掉name中的相同数据
相当于:select distict name from userInfo;
3、查询age = 22的记录
db.userInfo.find({"age": 22});
相当于: select * from userInfo where age = 22;
4、查询age > 22的记录
db.userInfo.find({age: {$gt: 22}});
相当于:select * from userInfo where age >22;
5、查询age < 22的记录
db.userInfo.find({age: {$lt: 22}});
相当于:select * from userInfo where age <22;
6、查询age >= 25的记录
db.userInfo.find({age: {$gte: 25}});
相当于:select * from userInfo where age >= 25;
7、查询age <= 25的记录
db.userInfo.find({age: {$lte: 25}});
8、查询age >= 23 并且 age <= 26
db.userInfo.find({age: {$gte: 23, $lte: 26}});
9、查询name中包含 mongo的数据
db.userInfo.find({name: /mongo/});
//相当于%%
select * from userInfo where name like ‘%mongo%';
10、查询name中以mongo开头的
db.userInfo.find({name: /^mongo/});
select * from userInfo where name like ‘mongo%';
11、查询指定列name、age数据
db.userInfo.find({}, {name: 1, age: 1});
相当于:select name, age from userInfo;
当然name也可以用true或false,当用ture的情况下河name:1效果一样,如果用false就是排除name,显示name以外的列信息。
12、查询指定列name、age数据, age > 25
db.userInfo.find({age: {$gt: 25}}, {name: 1, age: 1});
相当于:select name, age from userInfo where age >25;
13、按照年龄排序
升序:db.userInfo.find().sort({age: 1});
降序:db.userInfo.find().sort({age: -1});
14、查询name = zhangsan, age = 22的数据
db.userInfo.find({name: 'zhangsan', age: 22});
相当于:select * from userInfo where name = ‘zhangsan' and age = ‘22';
15、查询前5条数据
db.userInfo.find().limit(5);
相当于:selecttop 5 * from userInfo;
16、查询10条以后的数据
db.userInfo.find().skip(10);
相当于:select * from userInfo where id not in (
select top 10 * from userInfo
);
17、查询在5-10之间的数据
db.userInfo.find().limit(10).skip(5);
可用于分页,limit是pageSize,skip是第几页*pageSize
18、or与 查询
db.userInfo.find({$or: [{age: 22}, {age: 25}]});
相当于:select * from userInfo where age = 22 or age = 25;
19、查询第一条数据
db.userInfo.findOne();
相当于:select top 1 * from userInfo;
db.userInfo.find().limit(1);
20、查询某个结果集的记录条数
db.userInfo.find({age: {$gte: 25}}).count();
相当于:select count(*) from userInfo where age >= 20;
21、按照某列进行排序
db.userInfo.find({sex: {$exists: true}}).count();
相当于:select count(sex) from userInfo;
二、语句块操作
1、简单Hello World
print("Hello World!");
这种写法调用了print函数,和直接写入"Hello World!"的效果是一样的;
2、将一个对象转换成json
tojson(new Object());
tojson(new Object('a'));
3、循环添加数据
for (var i = 0; i < 30; i++) {
db.users.save({name: "u_" + i, age: 22 + i, sex: i % 2});
};
这样就循环添加了30条数据,同样也可以省略括号的写法
for (var i = 0; i < 30; i++) db.users.save({name: "u_" + i, age: 22 + i, sex: i % 2});
也是可以的,当你用db.users.find()查询的时候,显示多条数据而无法一页显示的情况下,可以用it查看下一页的信息;
4、find 游标查询
var cursor = db.users.find();
while (cursor.hasNext()) {
printjson(cursor.next());
}
这样就查询所有的users信息,同样可以这样写
var cursor = db.users.find();
while (cursor.hasNext()) {
printjson(cursor.next);
}
同样可以省略{}号
5、forEach迭代循环
db.users.find().forEach(printjson);
forEach中必须传递一个函数来处理每条迭代的数据信息
6、将find游标当数组处理
var cursor = db.users.find();
cursor[4];
取得下标索引为4的那条数据
既然可以当做数组处理,那么就可以获得它的长度:cursor.length();或者cursor.count();
那样我们也可以用循环显示数据
for (var i = 0, len = c.length(); i < len; i++) printjson(c[i]);
7、将find游标转换成数组
var arr = db.users.find().toArray();
printjson(arr[2]);
用toArray方法将其转换为数组
8、定制我们自己的查询结果
只显示age <= 28的并且只显示age这列数据
db.users.find({age: {$lte: 28}}, {age: 1}).forEach(printjson);
db.users.find({age: {$lte: 28}}, {age: true}).forEach(printjson);
排除age的列
db.users.find({age: {$lte: 28}}, {age: false}).forEach(printjson);
9、forEach传递函数显示信息
db.things.find({x:4}).forEach(function(x) {print(tojson(x));});
三、官方提供的操作语句对照表:
上行:SQL 操作语句
下行:Mongo 操作语句
CREATE TABLE USERS (a Number, b Number)
db.createCollection("mycoll")
INSERT INTO USERS VALUES(1,1)
db.users.insert({a:1,b:1})
SELECT a,b FROM users
db.users.find({}, {a:1,b:1})
SELECT * FROM users
db.users.find()
SELECT * FROM users WHERE age=33
db.users.find({age:33})
SELECT a,b FROM users WHERE age=33
db.users.find({age:33}, {a:1,b:1})
SELECT * FROM users WHERE age=33 ORDER BY name
db.users.find({age:33}).sort({name:1})
SELECT * FROM users WHERE age>33
db.users.find({'age':{$gt:33}})})
SELECT * FROM users WHERE age<33
db.users.find({'age':{$lt:33}})})
SELECT * FROM users WHERE name LIKE "%Joe%"
db.users.find({name:/Joe/})
SELECT * FROM users WHERE name LIKE "Joe%"
db.users.find({name:/^Joe/})
SELECT * FROM users WHERE age>33 AND age<=40
db.users.find({'age':{$gt:33,$lte:40}})})
SELECT * FROM users ORDER BY name DESC
db.users.find().sort({name:-1})
SELECT * FROM users WHERE a=1 and b='q'
db.users.find({a:1,b:'q'})
SELECT * FROM users LIMIT 10 SKIP 20
db.users.find().limit(10).skip(20)
SELECT * FROM users WHERE a=1 or b=2
db.users.find( { $or : [ { a : 1 } , { b : 2 } ] } )
SELECT * FROM users LIMIT 1
db.users.findOne()
SELECT DISTINCT last_name FROM users
db.users.distinct('last_name')
SELECT COUNT(*y) FROM users
db.users.count()
SELECT COUNT(*y) FROM users where AGE > 30
db.users.find({age: {'$gt': 30}}).count()
SELECT COUNT(AGE) from users
db.users.find({age: {'$exists': true}}).count()
CREATE INDEX myindexname ON users(name)
db.users.ensureIndex({name:1})
CREATE INDEX myindexname ON users(name,ts DESC)
db.users.ensureIndex({name:1,ts:-1})
EXPLAIN SELECT * FROM users WHERE z=3
db.users.find({z:3}).explain()
UPDATE users SET a=1 WHERE b='q'
db.users.update({b:'q'}, {$set:{a:1}}, false, true)
UPDATE users SET a=a+2 WHERE b='q'
db.users.update({b:'q'}, {$inc:{a:2}}, false, true)
DELETE FROM users WHERE z="abc"
db.users.remove({z:'abc'});
整理自 脚本之家