Oracle interview questions

Tough-HR-Interview-Questions

admin Interview questions, Oracle

Hello guys,
Are you preparing to attend an Oracle interview soon? Here are a few questions and answers you may find interesting.

1. What is RAW datatype?
Ans.
RAW data type is used in storing values in binary data format. The maximum size of a RAW in a table is 32767 bytes.

2. What is BLOB datatype?
Ans.
A BLOB data type is a binary string with a varying length which is used in storing two gigabytes memory. Length should be stated in Bytes for BLOB

3. What is NULL value in Oracle?
Ans.
NULL value represents unknown or missing data. It is used as a place holder or represented as a default entry indicating that no actual data is present.

4. What is WITH CHECK OPTION?
Ans.
The WITH CHECK option clause specifies the level of check to be done in DML statements. It aids in preventing changes to a view that would produce results not contained in the sub query.

5. What is the difference between varchar and varchar2 data types?
Ans.
Varchar can store up to 2000 bytes and varchar2 can store up to 4000 bytes. While Varchar will occupy space for NULL value, Varchar2 will not occupy any space. They are differentiated by space.

6. What is the use of NVL function?
Ans.
The NVL function is used for replacing NULL values with given or another value. E.g. NVL(Value, replace value)

Click here to read more about NVL functions.

7. How do we get field detail of a table?
Ans.
To get the field of a specified table use, Describe

8. What is an ALERT?
Ans.
An alert is a window which appears in the center of the screen and overlays a portion of the current play.

9. What is the fastest query method to fetch data from the table?
Ans.
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.

10. What is the parameter mode that can be passed to a procedure?
Ans.
The parameter modes that can be passed to a procedure are IN, OUT and INOUT

11. What is hash cluster?
Ans.
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.

12. What are SET operators?
Ans.
SET operators are used with two or more queries. The operators are Union, Union All, intersect and Minus.

Click here to read more about SET Operators.

13. What is a view?
Ans.
View is a logical table that is based on one or more tables and views. The tables which the view is based upon are called Base Tables and it contains no data.

If you have any questions please comment below or write me an email.

If you like this blog, do share with your friends and colleagues on your social media.
For more updates join my facebook group and do like my facebook page.

Thank you,
Kapil Kumar

Sharing is caring!

You May Also Like..

NULLIF

Oracle SQL_Null Related functions-3_NULLIF

Hi Aliens, Today, we will talk about another Null Related Function, NULLIF. You can read my notes on NVL, NVL2 […]

WHERE

SQL – WHERE clause

Hi DBgeek Army, Welcome back to the world of Oracle! Where clause helps to select desired rows or helps to […]

comments

Comment in SQL and PL-SQL

Hi DBgeek Army, Welcome back to the world of Oracle! Comments are very important aspects of our code. No matter […]

5 Comments

  1. Is NVL function only used for replacing null value or it can replaced any value. Can we use NVL function in place of update query type coz update has same functionality.

    1. Hi Chitrak,
      NVL function is used to replace Null value.
      I do not think if it is little similar to an UPDATE statement.
      Any example, please?

      A detailed Blog on NVL function is on the way.

      Thank you,

  2. Generally, hash cluster is used to optimize performance of the query. Rows are bound with a hash key and all bound rows reside in a same data block so the data retrieval process becomes faster.

Leave a Reply to admin Cancel reply

Your email address will not be published. Required fields are marked *