RDBMS stands for relational database management system. It is a database management system
based on the relational model of data. Most databases in widespread use today are based on this model .
A relational database has following major components:
2. Record or Tuple
3. Field or Column name or Attribute
A table is a collection of data represented in rows and columns. Each table has a name in database. For example, the following table “ EMPLOYEE ” stores the information of employees in database.
Record or Tuple
Each row of a table is known as record. It is also known as tuple. For example, the following row is a record that we have taken from the above table.
Field or Column name or Attribute
The above table “EMPLOYEE” has four fields : Emp_Id, Emp_Name, Emp_Addr & Emp_Age.
A domain is a set of permitted values for an attribute in table. For example, a domain of month-of-year can accept January, February,…December as values, a domain of dates can accept all possible valid dates etc. We specify domain of attribute while creating a table.
An attribute cannot accept values that are outside of their domains. For example, In the above table “EMPLOYEE”, the emp_Id field has integer domain so that field cannot accept values that are not integers for example, Emp_Id cannot has values like, “First”, 10.11 etc.
Instance and Schema
I have already covered instance and schema in a separate guide, you can refer the guide here
This is our next topic, I have covered the keys in detail in separate tutorials. You can refer the keys index here.