标签：mongodb
MongoDB is database storing document object, the type of which is called Bson.(like JSON);
Example: // document defination
Now after using command[db.posts.insert(doc)], you will insert record successfully if seeing the
The following picture.
One of the fundamental functions of MongoDB is to support query dynamically, which is the same as the troditional relational database, but more effiecieny than that.
Query expression objects document is also a bson-structure document. For example, we could use the following the command to find all the record in the collections:
In addition to Query expression object, Mongodb still support extra argument items. For example, you may only wanna return some certain fields. For example:
Example 1: return all the fields expect for tags;
Example 2: return dall fields expect for comments and tags=”albert”
Example 3: return the only field ’name’ and gender=’male’
Removing operation is used to remove records from the collections.Example:
Advice: It’s better to use _id as condition when executing the remove operation/
Attention: In some conditions, when you are ready to remove one record, maybe in the meantime the update operation is updating this record which makes the reomve operation failed. As for this case, you could add the $atomic field to avoid this case. For example:
Argument Description:
Criteria: the object used to set query conditions
Objnew: Object used to set update content.
Upsert: if record exists, it will update it. Else insert a new record.
Multi: if multi matches conditoin, it will update all the records.
Attention: By fault, mongoDB will update the first record that matches the query condition.
【MongoDB】The basic operation of Mongodb, Insert\Query\Delete\Update
标签：mongodb
原文地址：http://blog.csdn.net/sxb0841901116/article/details/39436507
