Database concepts

Databases keep the information in tables. Such data is organized in rows and columns. It is possible to filter data in a table by specifying a column condition. For example if a table contains data about cars, then it would be possible to filter cars with specific color. It would also be possible to specify multiple conditions such as color and number of doors.

There may be more than one table in a database. In fact only very small databases have only a single table, majority of databases have more than one table.

There could be NoSQL databases. These databases are more simpler than regular SQL databases. Relationship between tables is offloaded from database engines to servers that retrieve data.

Relationship between data is not done by a database engine, but relationships is done by servers that retrieve this data. It removes relationships between the data from a database server and offloads it to the layer that retrieves such data.

The advantage of doing so is the speed gain of retrieving the data and scaling of that system. In a traditional database scaling is vertical. As data grows, there is a need to invest in a better performing server. NoSQL database scale horizontally by adding more machines.

I am just giving an overview of databases here. There is a lot that can be said about databases, database management can be a full time job.

Out of SQL databases popular choices are: MsSQL, Oracle, DB2, MySQL and Postgres databases.

Out of NoSQL databases popular choices are: MongoDB, Casandra, DynamoDB.

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