mongodb 小操作

《mongodb 小操作》要点：
本文介绍了mongodb 小操作，希望对您有用。如果有疑问，可以联系我们。

mongodb-driver.jar操作数据库

collection是DBCollection对象

添加数据

collection.save(new BasicDBObject("author","yinjihuan").append("title","mongodb"));

编辑数据

collection.update(new BasicDBObject("author","yinjihuan"),

new BasicDBObject("$set",new BasicDBObject("title","mongodb3.0")));

删除数据

collection.remove(new BasicDBObject("author","yinjihuan"));

查询所有数量

long count = collection.count();

查询所有数据

DBCursor cursor = collection.find();

while (cursor.hasNext()) {

DBObject data = cursor.next();

System.out.println(data.toString());

}

查询第一条数据

DBObject data = collection.findOne();

带条件查询

DBObject query = new BasicDBObject("author","yinjihuan");

cursor = collection.find(query);

大于(gt)查询

query = new BasicDBObject("visit_count",new BasicDBObject("$gt",10));

cursor = collection.find(query);

小于(lt)查询

query = new BasicDBObject("visit_count",new BasicDBObject("$lt",10));

cursor = collection.find(query);

查询固定的列

query = new BasicDBObject("author","yinjihuan");

DBObject fields = new BasicDBObject("author",1);

cursor = collection.find(query,fields);

分页查询,当数据量较大的时候不建议使用skip,会很慢的

建议按id排序,每查询一页记住最后一条id,然后大于id在limit

query = new BasicDBObject("author","yinjihuan");

cursor = collection.find(query,fields).skip(0).limit(10);

创建索引

collection.createIndex(new BasicDBObject("author_idx",1));

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