What is Table?
The data in RDBMS is stored in database objects called tables. The table is a collection of related data entries and it consists of columns and rows.
- Remember, a table is the most common and simplest form of data storage in a relational
database. Following is the example of a STUDENT table:
What is Field?
- Every table is broken up into smaller entities called fields. The fields in the STUDENT table consist of s_id, s_name, s_age.
- A field is a column in a table that is designed to maintain specific information about every record in the table.
What is Record or Row?
- A record, also called a row of data, is each individual entry that exists in a table.
- For example there are 4 records in the above STUDENT table. Following is a singlerow of data or record in the STUDENT table:
Record is a Horizontal Entity in a table
What is Column?
A column is a vertical entity in a table that contains all information associated with a specific field in a table.
- For example, a column in the STUDENT table is s_name
What is NULL value?
- A NULL value in a table is a value in a field that appears to be blank which means a field with a NULL value is a field with no value.
- It is very important to understand that a NULL value is different than a zero value or a field that contains spaces. A field with a NULL value is one that has been left blank During record creation.