Java MongoDB Query (ii) complex queries

Objective

In the previous "Java MongoDB query (a) simple query" We have a simple look at the following query, but only those queries are not enough, but also need complex queries, this is described in this article.

1. Data structure

Collection: Firstcollection

Data content:

{"_id": ObjectId ("55adba52fa1f3cf038c2aea6"), "name": "User0", "Age": $, "Sex": 0}

{"_id": ObjectId ("55adba52fa1f3cf038c2aea7"), "name": "User1", "age": All, "Sex": 1}

{"_id": ObjectId ("55adba52fa1f3cf038c2aea8"), "name": "User2", "Age": $, "Sex": 0}

{"_id": ObjectId ("55adba52fa1f3cf038c2aea9"), "name": "User3", "age": +, "Sex": 1}

{"_id": ObjectId ("55ADBA52FA1F3CF038C2AEAA"), "name": "User4", "age": +, "Sex": 0}

{"_id": ObjectId ("55adba52fa1f3cf038c2aeab"), "name": "User5", "age": +, "Sex": 1}

2, connect the database, get the set firstcollection

Mongoclient mclient = new Mongoclient ("10.211.55.8");

DB db = Mclient.getdb ("test");

Dbcollection collection = Db.getcollection ("firstcollection");

3, and query

Operator: $and

Scenario: Querying an object with age greater than 23 and a sex of 1

Query criteria JSON content:

{"$and": [{"Age": {"$gt": 23}},{"Sex": 1}]}

Query condition Java content:

Basicdbobject ageobj = new Basicdbobject ("Age", New Basicdbobject ("$gt", 23));

Basicdbobject sexobj = new Basicdbobject ("Sex", 1);

Basicdbobject andobj = new Basicdbobject ("$and", Arrays.aslist (Ageobj,sexobj));

Execution process:

cursor cursor = Collection.find (andobj);

while (Cursor.hasnext ()) {

DBObject obj = Cursor.next ();

System.out.println (Obj.tostring ());

}

4, or query

Operator: $or

Scenario: Query for Name User2, or object named User3

Query criteria JSON content:

{"$or": [{"Name": "User2"},{"name": "User3"}]}

Query condition Java content:

Basicdbobject user2obj = new Basicdbobject ("name", "User2");

Basicdbobject user3obj = new Basicdbobject ("name", "User3");

Basicdbobject orobj = new Basicdbobject ("$or", Arrays.aslist (User2obj,user3obj));

Execution process:

cursor cursor = Collection.find (orobj);

while (Cursor.hasnext ()) {

DBObject obj = Cursor.next ();

System.out.println (Obj.tostring ());

}

5. Summary

Through the query with or, we understand the way of query conditions combination, in this way, and then contact the "Java MongoDB Query (a) Simple query" content can be combined into the various results we want to query conditions.

Java MongoDB Query (ii) complex queries