There is a wide range of books available in marks for ONGC Exam for Computer Science Discipline.

I am providing list of best books that helps to crack ONGC Exam for your reference.

Best Books for ONGC Exam

ONGC Computer Science Complete Book
(CD) Paperback
by Chandresh Agrawal & Team (Author)
Language: English
Publisher: Priyanka Prakashan
ASIN: B00NL78C2M

ONGC Electrical Assistant Executive Engineer Recruitment Examination (English) 1st Edition (Paperback)
Author: GKP
Language: English
Length: 835 pages
Publisher: GK Publications

ONGC Mechanical Assistant Executive Engineer Recruitment Examination (English) 1st Edition (Paperback)
Author: GKP
Language: English
Length: 620 pages
Publisher: GK Publications

ONGC Production Assistant Executive Engineer Recruitment Examination (English) 6th Edition (Paperback)
Author: GKP
Language: English
Length: 835 pages
Publisher: GK Publications

ONGC Electronics Assistant Executive Engineer - Recruitment Examination (English) 1st Edition (Paperback)
Author: GKP
Language: English
Length: 612 pages
Publisher: GK Publications

Khanna's GATE- Electronics & Communication Engineering: Complete Comprehensive Guide for GATE & PSU's BEL, Bhel, NTPC, HPCL, NALCO, ONGC, BSNL, DRDO, ISRO Previous Years' Solved Question Papers with Explanations (English) 1st Edition(Paperback)
Author: Sudakar Singh Chauhan
Language: English
Length: 536 pages
Publisher: KHANNA BOOK PUBLISHING-NEW DELHI

Here I am providing syllabus of ONGC Computer Science Exam:

ONGC Computer Science Exam Syllabus
Digital Logic: Logic functions, Minimization, Design and synthesis of combinational and sequential circuits; Number representation and computer arithmetic (fixed and floating point).

Computer Organization and Architecture: Machine instructions and addressing modes, ALU and data-path, CPU control design, Memory interface, I/O interface (Interrupt and DMA mode), Instruction pipelining, Cache and main memory, Secondary storage, Microprocessors (8085) – Architecture, Programming and Interfacing.
Theory of Computation: Regular languages and finite automata, Context free languages and Push-down automata, Recursively enumerable sets and Turing machines, Undecidability; NPcompleteness.

Programming and Data Structures: Programming in C/C++; Functions, Recursion, Parameter passing, Scope, Binding; Classes, Objects, Polymorphism, Abstract data types, Arrays, Stacks, Queues, Linked Lists, Trees, Binary search trees, Binary heaps.

Algorithms: Analysis, Asymptotic notation, Notions of space and time complexity, Worst and average case analysis; Design: Greedy approach, Dynamic programming, Divide-and-conquer; Tree and graph traversals, Connected components, Spanning trees, Shortest paths; Hashing, Sorting, Searching.

Compiler Design: Lexical analysis, Parsing, Syntax directed translation, Runtime environments, Intermediate and target code generation, Basics of code optimization.

Operating Systems: Processes, Threads, Inter-process communication, Concurrency, Synchronization, Deadlock, CPU scheduling, Memory management and virtual memory, Filesystems, I/O systems.

Databases: ER-model, Relational model (relational algebra, tuple calculus), Database design (integrity constraints, normal forms), Query languages (SQL), File structures (sequential files, indexing, B and B+ trees), Transactions and concurrency control.

Computer Networks: ISO/OSI and TCP/IP stacks, Ethernet, Flow and error control techniques, Routing algorithms, Congestion control, IP(V4) and its addressing schemes, TCP/UDP and sockets, Basic concepts of hubs, switches, gateways, and routers