Serializability is the concurrency scheme. 

Serializability ensures that a schedule for executing concurrent transactions is equivalent to one that executes the transactions serially in some order. 

It assumes that all accesses to the database are done using read and write operations.

Let’s take a simple example:


In this SQL query, two transactions are running concurrently updation of salary and searching of employee no.

Conflict serializability:

Instructions I1 and I2 of transactions T1 and T2 respectively, conflict if and only if there exists some item A accessed by both I1 and I2, and at least one of these instructions write A.

1. I1 = Read(A),  I2 = Read(A).   I1 and I2 don’t conflict.
2. I1 = Read(A),  I2 = Write(A).  They conflict.
3. I1 = Read(A),  I2 = Write(A).  They conflict
4. I1 = Read(A),  I2 = Write(A).  They conflict

Check out this video lecture, for more info on Serializability

More topics from DBMS to read:


  1. Korth, Silbertz,Sudarshan, “Fundamental of Database System”, McGraw Hill
  2. Atul Kahate , “ Introduction to Database Management System”, Pearson Educations

Python Programming ↓ 👆
Java Programming ↓ 👆
JAVA covered following topics in these notes.
JAVA Programs
Principles of Programming Languages ↓ 👆
Principles of Programming Languages covered following topics in these notes.

Previous years solved papers:
A list of Video lectures References:
  1. Sebesta,”Concept of programming Language”, Pearson Edu 
  2. Louden, “Programming Languages: Principles & Practices” , Cengage Learning 
  3. Tucker, “Programming Languages: Principles and paradigms “, Tata McGraw –Hill. 
  4. E Horowitz, "Programming Languages", 2nd Edition, Addison Wesley

    Computer Organization and Architecture ↓ 👆

    Computer Organization and Architecture covered following topics in these notes.

    1. Structure of desktop computers
    2. Logic gates
    3. Register organization
    4. Bus structure
    5. Addressing modes
    6. Register transfer language
    7. Direct mapping numericals
    8. Register in Assembly Language Programming
    9. Arrays in Assembly Language Programming


    1. William stalling ,“Computer Architecture and Organization” PHI
    2. Morris Mano , “Computer System Organization ”PHI

    Computer Network ↓ 👆
    Computer Network covered following topics in these notes.
    1. Data Link Layer
    2. Framing
    3. Byte count framing method
    4. Flag bytes with byte stuffing framing method
    5. Flag bits with bit stuffing framing method
    6. Physical layer coding violations framing method
    7. Error control in data link layer
    8. Stop and Wait scheme
    9. Sliding Window Protocol
    10. One bit sliding window protocol
    11. A protocol Using Go-Back-N
    12. Selective repeat protocol
    13. Application layer
    1. Andrew S. Tanenbaum, David J. Wetherall, “Computer Networks” Pearson Education.
    2. Douglas E Comer, “Internetworking with TCP/IP Principles, Protocols, And Architecture",Pearson Education
    3. KavehPahlavan, Prashant Krishnamurthy, “Networking Fundamentals”, Wiley Publication.
    4. Ying-Dar Lin, Ren-Hung Hwang, Fred Baker, “Computer Networks: An Open Source Approach”, McGraw Hill.