How DBMS differ from RDBMS?

Question

Is this how they differ, This is what I have understood.

DBMS

stored data in files , that computer hard disk is a DBMS since it stored data in Disks. And there are no such thing called Tables and relationships between tables no Primary keys, No foreign keys.

And used for simple small applications. Security is not concerned.

RDBMS 

Stores data in tables , has relationships between tables, can do normalization. RDBMS is a DBMS. MS Access , SQL server , MYSQL are RDBMS. And RDBMS used for huge databases. Supports Client server architecture.

Now I need to clarify,

1. DBMS example is hard disk data storage. Is RDBMS for software applications data storage?

2. It says DBMS is for small data-storage and RDBMS for large data storage. If 1. is true then, doesn't hard disk contain a huge amount of data?.

3. How security come to issue? Why DBMS does not have security and HOW RDBMS have a security?

4. So we can create a RDBMS using MySQL, SQL Server etc. How can we create a DBMS?

5. And finally what else differences are there than what I found?

Answer 1

Firstly let's define the meaning of the two letters DB in both abbreviations:

DB stands for Database. The definition of Wikipedia is the following:

A database is an organized collection of data. The data are typically organized to model relevant aspects of reality in a way that supports processes requiring this information. For example, modelling the availability of rooms in hotels in a way that supports finding a hotel with vacancies.

So roughly said, any kind of data stored on a computer device is a component of a database. The Database is the data itself. It does not self-include information of how this data should be organized, retrieved, deleted, manipulated etc., it simply exists on the hard drive.

This job is being done by the management system, what actually is the meaning of the two letters MS. This system is responsible or all kinds of operations of the data. Again Wikipedia says:

Database management systems (DBMSs) are specially designed software applications that interact with the user, other applications, and the database itself to capture and analyze data. A general-purpose DBMS is a software system designed to allow the definition, creation, querying, update, and administration of databases. Well-known DBMSs include MySQL, MariaDB, PostgreSQL, SQLite, Microsoft SQL Server, Microsoft Access, Oracle, SAP HANA, dBASE, FoxPro, IBM DB2, LibreOffice Base, FileMaker Pro and InterSystems Caché.

So let's go through the points you have mentioned.

1. I assume that you refer to how the data is organized within the database. DBMS is a generic term, which means that the term itself does not contain information on how the data should be exactly stored. Possible options are the usage of relational tables (tables, which contain attributes and have relationships between each other roughly said), files, graphs, key-value pairs etc. A RDBMS is DBMS which uses relational tables to store the data. Examples of non-relational DBMS's are a file system or NoSQL.

2. When in this case it depends, this conclusion is generally wrong. It is up to the specific implementation of the DBMS of how it s going to operate with the data. Generally said, it depends on the use case.

3. Again very specific subject. A DBMS with no internal organization will keep the files simply in memory, which means that their content could be easily retrieved, where the RDBMS will always need a specific knowledge of the system in order to extract the content. This does not automatically mean, that each DBMS, which is not using relational tables as data storage, will have no internal organization of the structure, therefore 0-level security. Each specific DBMS has it's own way to overcome possible security issues.

4. MySQL, SQL Server etc. are RDBMS therefore DBMS themselves. The way they organize data is using the relational model. There are another opportunities like NoSQL to store the data in a different manner.

5. You pretty much covered all of the basic points. Performance measure could also be included, but it is again subjective thema. There are some other aspects, which are really DBMS specific, like concurrency management, complexity etc.

Answer 2

Hope the following answers might help.

1. For DBMS, you can say it is Hard disk data storage. Data is stored in flat files. There is not relation between the tables. Relations are maintained programmatically but not by the database itself.
2. No, both DBMS and RDBMS are used for storing data, small or Huge. For example mainframes have non-relational data (huge amounts of it) and are still in use as legacy systems.
3. Well DBMS(essentially non-relational data) are simply stored in flat files. It is easy to get hold of them and transfer them if you have access to the file system :) . RDBMS, even though some use files, reading data from the files is a bit trivial. And need to have absolute knowledge about the system to convert the data, again you should have access to the file system which is at the same high level for both DBMS and RDBMS.
4. DBMS is currently in place as legacy system. COBOL maybe can create DBMS.
5. You essentially covered everything. :D

Answer 3

The 3 most important concepts concerning RDBMS are :

• semantics
• logic
• transactions

Semantics: means that data are not retrieved by a "hardware" approach like "some bytes equals some other bytes", but by the fact that "information equals information", whatever the encoding is

logic: the RDBMS features are based on a theoretical mathematic approach call "relational algebra" and this theory has been established by Franck Edgar Cood in a 1970 paper called "A Relational Model of Data for Large Shared Databanks" and works Always since 1970 on this concept (50 years !!!)

transactions: dataset operations are ever atomic, which means that one operation can deal with a very huge amount of data and must, finally, execute all the transformation conforming to the internal rules of the database, or come back to the starting point.

Some DBMS pretending to be relational does not…. This is the case for MySQL and PostgreSQL!

In 1985, Codd saw many products pretendig to be relationnal but had nothing to do with relationnal concepts. So, he wroted 2 papers in Computer Science magazine, called : - is your DBMS really relationnal ? - does your DBMS runs by the rules ? And in the second paper, edicted the 12 codd's rules to see how relationnal a product is.

One of this rules is the 7th and speaks about set based operations. As an illustration of this rule, I give the Following example in my courses for engineering schools :

CREATE TABLE T (C INT UNIQUE);
INSERT INTO T VALUES (1), (2), (3);
UPDATE T SET C = C + 1;

The last query must never fail because all the values (1, 2, 3) are simultaneously updated, so there is no conflicts with the UNIQUE constraint.

PostgreSQL and MySQL (and some more others) fails when executing the last query becauses they operates in an iterative process which is not the intimate way to manipulate sets of datas…

This query is correctly executed on the major RDBMS like Oracle, SQL Server, DB2 or Sybase…

Answer 4

1.DBMS applications store data as file. In DBMS, data is generally stored in either a hierarchical form or a navigational form. DBMS is meant to be for small organization and deal with small data. it supports single users. Examples:-file systems, xml etc.

2.RDBMS applications store data in a tabular form. In RDBMS, the tables have an identifier called primary key and the data values are stored in the form of tables. RDBMS is designed to handle large amount of data. it supports multiple users. Example:-mysql, postgre, sql server, oracle ,Mango DB etc.

3.Every RDBMS is a DBMS, but the opposite is not true: RDBMS is a DBMS which is based on the relational model, but not every DBMS must be relational.

4.However, since RDBMS are most common, sometimes the term DBMS is used to denote a DBMS which is NOT relational. It depends on the context.