Overview of Database Fields
A database is a collection of tables. Each table has fields, or containers, to hold the data, and each table contains rows of data, which are also called records.
Consider a student table that stores data about students in a class, like this one here:
Student Table
| student-id |
student-name |
student-email |
| 054 |
Joe |
j@email.com |
| 055 |
Kate |
k@email.com |
| 056 |
Laura |
l@email.com |
| 057 |
Mike |
m@email.com |
As we can see, the fields in this table (which are the containers that hold the data) are:
- Student-id
- Student-name
- Student-email
This table has four rows of data. Each row is a database record. A record for this table contains all the information about one student. Each of the columns of the table, (student-id, student-name, and student-email) are the database fields. In this table, record 1 is data about the student Joe, his student ID is 054, and his email is j@email.com.
Each database field defines a unique piece of data. A table contains only one field of each kind. For example, the student table will have only one field each for student ID, student name, and student email. There will not be two student ID fields, for instance.
Example
The fields in the student table can be described as follows:
- Student-id: is an ID assigned to each of the students
- Student-name: is the first and last name of each student
- Student-email: is the email address of each student
The database field names are descriptive of the data they contain. When you see the field 'student-id' you can tell that this field contains the ID of each student. And when you see the 'student-email' field, you can tell that this field contains the email address of each student.
In the database table, each field is in a column. In the above example, 'student-id' is in the first column, 'student-name' is in the second column, and 'student-email' is in the third column.
When a database table is created, the fields have to be determined to help decide what kind of data will be stored in the table. This is like saying that when a house is built, you have to decide how many rooms there will be and what the function of each room is. For example, you would have a kitchen where you do your cooking, a living room where you relax, and so on. Similarly, in the student table, you define a field, or container, called 'student-id' to save the student IDs of all students; you define a field, or container, called 'student-name' to save the names of all students; and so on.
