Data model describes the structure of a database. Data model is collection of conceptual tools for describing data, relationship etc. It explains how the data are stored in the database. Data modeling is the process of using data model for maintaining database.
Different data modeling techniques used are:
- Hierarchical model
- Network model
- Relational model
DML (Data Manipulation Language)
Data Manipulation Language is a database language used for database operations such as inserting, accessing, updating, deleting data etc. DML are of two types:
1. Procedural DML: In this type of DML, the developer has to define the process of database operation.
2. Declarative DML: In this type of DML, the developer doesn’t require to define the process of database operation. So, it is easier for the developer but it can be used only for limited operation.