MongoDB vs SQL Terminology
MongoDB is a NoSQL product so the terminology is used in SQL not used in MongoDB, but the comparing SQL things with NoSQL will speedup the learning process.
| Terminology | Description | |
| 1 | field | A name-value pair. It is similar concept of column of an RDBMS | 
| 2 | document | A group of fields are termed as document. In RDBMS we will term it as row. MongoDB document follows JSON syntax but it is a BSON syntax (BSON is an extended version of JSON implemented by MongoDB). | 
| 3 | collection | A group of documents called collection in MongoDB. A collection is similar concept of table of an RDBMS. | 
| 4 | database | A Physical Container for Collections. Each database gets its own set of files on the file system. A single MongoDB server typically has multiple databases | 
Let’s view this Table presents the various SQL terminology and concepts and the corresponding MongoDB terminology and concepts.
| SQL Terms | MongoDB Terms | |
| database | database | |
| table | collection | |
| row | document or BSON document | |
| column | field | |
| index | index | |
| table joins | embedded documents and linking | |
| primary key Specify any unique column or column combination as primary key. | primary key In MongoDB, the primary key is automatically set to the _id field. | |
| aggregation (e.g. group by) | aggregation pipeline | 
| SQL Concepts | MongoDB Aggregation Operators | |
|---|---|---|
| WHERE | $match | |
| GROUP BY | $group | |
| HAVING | $match | |
| SELECT | $project | |
| ORDER BY | $sort | |
| LIMIT | $limit | |
| SUM() | $sum | |
| COUNT() | $sum | |
| join | $lookup | 
Executables Comparison
The following table presents some database executables and the corresponding MongoDB executables. This table is not meant to be exhaustive.
| MongoDB | MySQL | Oracle | Informix | DB2 | |
|---|---|---|---|---|---|
| Database Server | mongod | mysqld | oracle | IDS | DB2 Server | 
| Database Client | mongo | mysql | sqlplus | DB-Access | DB2 Client |