What is RDBMS (Relational Database Management Systems)?

What is RDBMS? Well, technically it stands for Relational Database Management Systems. It is the name of the system used to store, administer, query, and retrieve data from a relational database (RDBMS). The RDBMS offers administrative features for controlling data storage, access, and performance as well as an interface between users, applications, and the database.

This relational model was introduced by E. F. Codd and even today RDBMS is the basis of all modern database systems such as MySQL, Microsoft SQL Server, Oracle, etc.

What is RDBMS Table?

The records or data stored in RDBMS are in the form of objects that are known as Tables. It is a collection of related records or data and it also consists of different columns & rows. A record is an individual entry that exists in the table whereas the column holds information about every record in the table. Storing the data or records in a table is the easiest form of storage in RDBMS.

RDBMS Table Structure

We will look at the structure of how the data is stored in RDBMS. Here we are looking at a small table on Products Order information named (Products).

Order ID Category Region City Country Customer_ID Customer_name
CA-2018-126907 Office Supplies Central Chicago United States SM-20950 Suzanne McNair
CA-2021-115546 Technology East New York City United States AH-10465 Amy Hunt
CA-2021-115546 Office Supplies East New York City United States AH-10465 Amy Hunt
CA-2019-163587 Office Supplies East Dover United States EP-13915 Emily Phan
CA-2019-163587 Office Supplies East Dover United States EP-13915 Emily Phan
US-2021-106131 Technology West Aurora United States TP-21565 Tracy Poddar
US-2021-106131 Office Supplies West Aurora United States TP-21565 Tracy Poddar
CA-2019-160213 Office Supplies East Long Beach United States AR-10825 Anthony Rawles
CA-2018-157924 Office Supplies West Pasadena United States HA-14920 Helen Andreada
CA-2018-157924 Furniture West Pasadena United States HA-14920 Helen Andreada

The columns in the “Products” table above are Category, Region, City, Country, Customer ID, and Customer Name.

The database defines relationships in the form of tables. The tables are related to each other on data common in them. The relationship between the “Products$” table and the “People$” table is the Region column:

Region Regional Manager
West Sadie Pawthorne
East Chuck Magee
Central Roxanne Rodriguez
South Fred Suzuki

Similarly, the relationship between the “Products” table and the “Returns$” table is the Order ID column-

Order ID Returned
CA-2018-126907 Yes
CA-2021-115546 Yes
CA-2021-115546 Yes
CA-2019-163587 Yes
CA-2019-163587 Yes
US-2021-106131 Yes
US-2021-106131 Yes
CA-2019-160213 Yes
CA-2018-157924 Yes
CA-2018-157924 Yes

 

What is a FIELD in RDBMS?

A field is a column name that defines each record specifically. As in the above table, we have OrderDate, Region, Rep, Item, Units, Unit Cost, and Total are all Fields.

What is a Column in RDBMS?

A column is a vertical entity in a table that contains all information associated with a field in a table.

For example, a column in the Products table is Region, which represents region description as shown below –

Category
Office Supplies
Technology
Furniture

NULL Values –

NULL values are those values in a field that appears to be blank, which means the field is NULL with no value. It’s very important to understand that the NULL values are not equivalent to zero or spaces. It is the field that is intentionally kept blank at the time of data creation.

Other SQL topics to check out:

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