mongodb $操作

db.test.insert([
{"name":"xiaoming","age":"10"},
{"name":"xiaohong","age":"20"},
{"name":"xiaolan","age":"30"},
{"name":"xiaolv","age":"40"},
{"name":"xiaozi","age":"50"},
{"name":"xiaohei","age":"60"}
]);

db.test.find();

db.test.find({$or:[{"age":"10"},{"name":"xiaoming"}]});

db.test.createIndex({"age" : 1});

db.test.find({"age" : {$in : ["10","20"]}});

//$lte小于  $ne 不等于
db.test.find({$and : [{"age":{$ne : "10"}},{"age" :{$lte : "30"}}]});

//$exists 字段非空
db.test.find({
$and : [
        {"age":{$ne : "10"}},
        {"name" :{$exists : true}}
        ]
});

//使用$and拼接大量的 条件, 两个or之间是且的关系, 第一个返回false 后边不会执行
db.test.find(
    {
        $and : [
            {
                $or : [{ "name":"xiaoming"} , {"name":"xiaohong"}]
            },
            {
                $or : [{ "age" : "20" },{"age" : "30"}]
            }    
        ]
    }
)