Oracle Interview Questions and Answers For Freshers

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.
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
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.
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.
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.
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)
How do we get field detail of a table?
Ans.To get the field of a specified table use, Describe
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.
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.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
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.
What are SET operators?
Ans.SET operators are used with two or more queries. The operators are Union, Union All, intersect and Minus.

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