Oracle Interview Questions and Answers, Oracle Interview Questions and Answers Freshers, Oracle Interview Questions and Answers, Oracle Interview Questions
Before getting on to the Oracle interview questions, the student must know that the Oracle is a continuously varying field which needs the students as well as professionals to upgrade their skills with the new features and knowledge, to get fit for the jobs associated with Oracle. This post related to Oracle Interview Questions and Answers, Oracle Interview Questions and Answers Freshers, Oracle Interview Questions and Answers, Oracle Interview Questions will help you let out find all the solutions that are frequently asked in you upcoming Oracle interview.
Over thousands of vacancies available for the Oracle developers, experts must be acquaintance with all the component of Oracle technologies. This is necessary for the students in order to have in-depth knowledge of the subject so that they can have best employment opportunities in the future. Knowing every little detail about Oracle is the best approach to solve the problems linked to the problem.
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First of all, let us tell you about how the Oracle technology is evolving in today’s world and how demanding it is in the upcoming years. In fact, according to one study, most of the companies and businesses have moved to the Oracle. Now, you cannot predict how huge the future is going to be for the people experienced in the related technologies.
Hence, if you are looking for boosting up your profile and securing your future, Oracle will help you in reaching the zenith of your career. Apart from this, you would also have a lot of opportunities as a fresher.
These questions alone are omnipotent. Read and re-read the questions and their solutions to get accustomed to what you will be asked in the interview. These Oracle interview questions and answers will also help you on your way to mastering the skills and will take you to the giant world where worldwide and local businesses, huge or medium, are picking up the best and quality Oracle professionals.
This ultimate list of best Oracle interview questions will ride you through the quick knowledge of the subject and topics like Oracle, dimensional data structures. This Oracle interview questions and answers can be your next gateway to your next job as an Oracle expert.
These are very Basic Oracle Interview Questions and Answers for freshers and experienced both.
Q1: Oracle DBA Characteristics
A1:
Criteria Result
Main storage structures Logical and Physical
Architecture Grid architecture
ACID Compliance Fully compliant
Data stored as Data blocks, extents, segments and table spaces
Q2: What is Oracle?
A2: Oracle is a company. Oracle is also a database server, which manages data in a very structured way. It allows users to store and retrieve related data in a multi user environment so that many users can concurrently access the same data. All this is accomplished while delivering high performance. A database server also prevents unauthorized access and provides efficient solutions for failure recovery. A standby database is a database replica created by taking a backup of a primary database.
Q3: What is a Oracle Database?
A3: Oracle provides software to create and manage the Oracle database. The database consists of physical and logical structures in which system, user, and control information is stored. The software that manages the database is called the Oracle database server. Collectively, the software that runs oracle and the physical database are called the Oracle database system. A database buffer cache stores the data in memory for quicker access. The redo logs track and store all the changes made to the database. A Data Guard ensures data protection and high availability of data and control file records the physical structure of the database. Click on the above link to read more and to become a Oracle DBA.
Q4: What are the roles of DBA?
A4: DBA has the authority to create new users, remove existing users or modify any of the environment variables or privileges assigned to other users.
• Manage database storage
• Administer users and security
• Manage schema objects
• Monitor and manage database performance
• Perform backup and recovery
• Schedule and automate jobs
Q5: What are different Oracle database objects?
A5:
• TABLES
• VIEWS
• INDEXES
• SYNONYMS
• SEQUENCES
• TABLESPACES
Q6: What are the benefits of ORDBMS?
A6: The objects as such can be stored in the database. The language of the DBMS can be integrated with an object- oriented programming language. The language may even be exactly the same as that used in the application, which does not force the programmer to have two representations of his objects.
Q7: What is an Oracle index?
A7: An index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
Q8: What are the Common Oracle DBA Tasks?
A8: As an Oracle DBA, you can expect to be involved in the following tasks:
• Installing Oracle software
• Creating Oracle databases
• Performing upgrades of the database and software to new release levels
• Starting up and shutting down the database
• Managing the database’s storage structures
• Managing users and security
• Managing schema objects, such as tables, indexes, and views
• Making database backups and performing recovery when necessary
• Proactively monitoring the database’s health and taking preventive or corrective action as required
• Monitoring and tuning performanceIn a small to midsize database environment, you might be the sole person performing these tasks. In large enterprise environments, the job is often divided among several DBAs, each with their own area of specialty, such as the database security administrator or database tuning expert.
Q9: Difference between varchar and varchar2 data types?
A9: Varchar can store upto 2000 bytes and varchar2 can store upto 4000 bytes. Varchar will occupy space for NULL values and Varchar2 will not occupy any space. Both are differed with respect to space.
Q10: In which language Oracle has been developed?
A10: Oracle has been developed using C Language.
Q11: What is RAW datatype?
A11: RAW datatype is used to store values in binary data format. The maximum size for a raw in a table in 32767 bytes.
Q12: What is the use of NVL function?
A12: The NVL function is used to replace NULL values with another or given value. Example is –
NVL(Value, replace value)
Q13: Whether any commands are used for Months calculation? If so, What are they?
A13: In Oracle, months_between function is used to find number of months between the given dates. Example is –
Months_between(Date 1, Date 2)
Q14: What are nested tables?
A14: Nested table is a data type in Oracle which is used to support columns containing multi valued attributes. It also hold entire sub table.
Q15: What is Overloading of procedures ?
A15: The same procedure name is repeated with parameters of different datatypes and parameters in different positions, varying number of parameters is called overloading of procedures.
Q16: What is a package ? What are the advantages of package ?
A16: database object that groups logically related procedures.
The advantages of packages are modularity, easier application design, information hiding, reusability and better performance
Q17: What is difference between TRUNCATE and DELETE?
A17: Truncate is Dml Statements. Cannot be rolled back. Delete allows the filtered deletion.
Deleted records can be rolled back or committed.
Q18: What is a join? Explain the different types of joins?
A18: Join is a query,retrieves data from related columns or rows from multiple tables.
Self join – Joining the table with itself
Equi Join – Joining two tables by equating two common columns
Non Equi Join – Joining two tables based on conditions other than equating two common columns
Outer Join – Joining two tables in such a way that query can also retrieve rows that do not have the corresponding join value in the other table.
Q19: What is a Subquery?
A19: Subquery is a query embedded with another Query
Outer Query based on the Inner Query
Q20: What is correlated sub-query?
A20: Correlated sub-query is a sub-query, which has reference to the main query.
Q21: How do we get field detail of a table?
A21: To get the field of a specified table use, Describe <Table_Name>
Q22: What is an ALERT?
A22: An alert is a window which appears in the center of the screen and overlays a portion of the current play.
Q23: What is the fastest query method to fetch data from the table?
A23: You can use ROWID to fetch Row from the table. The use of ROW ID is the fastest query method for fetching data from the table.
Q24: What is the parameter mode that can be passed to a procedure?
A24: The parameter modes that can be passed to a procedure are IN, OUT and INOUT
Q25: What is hash cluster?
A25: Hash Cluster is a technique used for storing the table to make it faster to retrieve. It order to retrieve the rows from the table, apply the hash value on the table.
Q26: How many memory layers are in the Oracle shared pool?
A26: Oracle shared pools contains two layers:
1. library cache
2. data dictionary cache
Q27: What is save point in Oracle database?
A27: Save points are used to divide a transaction into smaller parts. It allows rolling back of a transaction. Maximum five save points are allowed. It is used to save our data, whenever you encounter an error you can roll back from the point where you save your SAVEPOINT.
Q28: What is hash cluster in Oracle?
A28: Hash cluster is a technique to store a data in hash table and improve the performance of data retrieval. Hash function is applied on table row’s cluster key value and store in hash cluster.
Q29: What are the various Oracle database objects?
A29: Tables: This is a set of elements organized in vertical and horizontal fashion.
Tablespaces: This is a logical storage unit in Oracle.
Views: It is virtual table derived from one or more tables.
Indexes: This is a performance tuning method to process the records.
Synonyms: This is a name for tables.
Q30: What is the difference between pre-select and pre-query?
A30: A pre-query trigger fire before the query executes and fire once while you try to query. With the help of this trigger you can modify the where clause part dynamically.
Pre-select query fires during the execute query and count query processing after Oracle forms construct the select statement to be issued, but before the statement is actually issued.
Pre-query trigger fires before Pre-select trigger.
Q31: Will you be able to store pictures in the database?Explain.
A31: – Yes, pictures can be stored in the database using Long Raw Data type.
– This datatype is used to store binary data for 2 gigabytes of length.
– However, the table can have only one Long Raw data type.
Q32: Explain: a.) Integrity constraint. b.) COALESCE function
A32: a.) Integrity constraint.
– It is a declaration defined in a business rule for a table column.
– Integrity constraint ensures the accuracy and consistency of data in a database.
– It is of three types – namely – Domain Integrity, Referential Integrity and Domain Integrity.
b.) COALESCE function
– This function is used to return the value which is set not to be null in the list.
– Incase all values in the list are null the coalesce function will return NULL.
– Its representation:
Q33: What are the various Oracle Database objects?
A33: Various database objects are as follows:
– Tables – This is a set of elements organized in vertical and horizontal fashion.
– Tablespaces – This is a logical storage unit in Oracle.
– Views – It is virtual table derived from one or more tables.
– Indexes – This is a performance tuning method to process the records.
– Synonyms – This is a name for tables.
– Sequences.
Q34: Differentiate between pre-select and pre-query.
A34: – Once oracle forms construct the select statement to be issued Pre-select is fired during the execute query and count query processing. All this happens before the statement is actually issued.
– The pre-query trigger is fired just before oracle forms issue the select statement to the database.
Q35: What is hot backup and logical backup?
A35: Hot backup
– Backing up the archive log files when database is open is called Hot backup.
– To do this, the ARCHIVELOG mode is enabled.
– Following files are backed up – All data files, Archive log, redo log files and control files.
Logical backup
– Logical back ip is reading a set of database records and writing them into a file.
– An Export utility is required to take the backup while an Import utility is required to recover from the backup.
Oracle Conclusion Interview FAQs
We know the list of Oracle Interview Questions and Answers, Oracle Interview Questions and Answers Freshers, Oracle Interview Questions and Answers, Oracle Interview Questions is overwhelming but the advantages of reading all the questions will maximize your potential and help you crack the interview. The surprising fact is that this Oracle interview questions and answers post covers all the basic of the Oracle technology and you have to check out the FAQs of different components of Oracle too.
However, you will be asked with the questions in the interview related to the above mentioned questions. Preparing and understanding all the concept of Oracle technology will help you strengthen the other little information around the topic.
After preparing these interview questions, we recommend you to go for a mock interview before facing the real one. You can take the help of your friend or a Oracle expert to find the loop holes in your skills and knowledge. Moreover, this will also allow you in practicing and improving the communication skill which plays a vital role in getting placed and grabbing high salaries.
Remember, in the interview, the company or the business or you can say the examiner often checks your basic knowledge of the subject. If your basics is covered and strengthened, you can have the job of your dream. The industry experts understand that if the foundation of the student is already made up, it is easy for the company to educate the employ towards advance skills. If there are no basics, there is no meaning of having learnt the subject.
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We hope that you enjoyed reading Oracle Interview Questions and Answers, Oracle Interview Questions and Answers Freshers, Oracle Interview Questions and Answers, Oracle Interview Questions and all the FAQs associated with the interview. Do not forget to revise all the Oracle interview questions and answers before going for the Oracle interview. In addition to this, if you’ve any doubt or query associated with Oracle, you can contact us anytime. We will be happy to help you out at our earliest convenience. At last, we wish you all the best for your upcoming interview on Oracle Technology.
