Deep in MongoDB(C++ API)

BSONObjBuilder Q;Q.append("Name", str);auto_ptr<DBClientCursor> cursor = conn.query("test".NewsContents", Q.obj());

查詢可以通過上面這句.然後條件分別append進去.

下面列出常見的幾種語句:

1. << or >>

BSONObj test = BSON("$lte"<<2011)Q.append("EntryTime", test);

2.在數組中進行(between and)匹配 [1,2,3,4,5,6,7,8]

BSONObj test=BSON("$gte"<<"0000"<<"$lte"<<"0001");BSONObj TestElemMatch=BSON("$elemMatch"<<test);Q.append("Category", TestElemMatch);

3. (3<A<=4) or (A<=3)
->Shell:

db.test.find({"$or":[{"A":{$elemMatch:{"$gt":3,"$lte":4}}},{"A":{$elemMatch:{"$lte":4}}}]})

->C++

BSONObj ACon1=BSON("$gt"<<3<<"lte"<<4);BSONObj ACon2=BSON("$lte"<<3);BSONObj AElemMatch1=BSON("$elemMatch"<<ACon1);BSONObj AElemMatch2=BSON("$elemMatch"<<ACon2);BSONObj A1=BSON("A"<<AElemMatch1);BSONObj A2=BSON("A"<<AElemMatch2);vector<BSONObj> con;con.push_back(A1);con.push_back(A2);Q.append("$or",con);