![]() This statement can be used with Foreign Keys. Q #9) How does the ON-DELETE-CASCADE statement work?Īnswer: Using ON DELETE CASCADE will automatically delete a record in the child table when the same is deleted from the parent table. Q #8) How can we find out the duplicate values in an Oracle table?Īnswer: We can use the below example query to fetch the duplicate records. ![]() INSTR will return the position number of the sub-string within the string.SUBSTR function returns the sub-part identified by numeric values from the provided string.Q #7) What is the difference between SUBSTR & INSTR functions? There are various types of Joins as listed below: Q #6) What is meant by Joins? List the types of Joins.Īnswer: Joins are used to extract data from multiple tables using some common columns or conditions. This data type can only be queried or inserted in a table. The difference between RAW & VARCHAR2 datatype is that PL/SQL does not recognize this data type and hence, cannot do any conversions when RAW data is transferred to different systems. The TRUNCATE command will free the object storage space while the DELETE command does not.Īnswer: RAW datatype is used to store variable-length binary data or byte strings.It can not be rolled back as it issues COMMIT before and after the command execution while the DELETE command can be rolled back. TRUNCATE removes all the rows but leaves the table structure intact.TRUNCATE is a DDL operation while DELETE is a DML operation.Q #4) What is the difference between TRUNCATE & DELETE commands?Īnswer: Both commands are used to remove data from the database. VARCHAR will hold the space for characters defined during declaration even if all of them are not used whereas VARCHAR2 will release the unused space.VARCHAR can store characters up to 2000 bytes while VARCHAR2 can store up to 4000 bytes.Q #3) How will you differentiate between VARCHAR & VARCHAR2?Īnswer: Both VARCHAR & VARCHAR2 are Oracle data types that are used to store character strings of variable length. Release 10.1.0.1.1 can be referred to as: Q #2) How will you identify Oracle Database Software Release?Īnswer: Oracle follows a number of formats for every release. It is widely used for online transaction processing, data warehousing, and enterprise grid computing. ![]() Q #1) What is Oracle and what are its different editions?Īnswer: Oracle is one of the popular databases provided by Oracle Corporation, which works on relational management concepts, and hence it is referred to as Oracle RDBMS as well. Let’s go ahead!! List Of Top Oracle Interview Questions If you are planning to appear for an Oracle interview, these sets of questions covered in this article will definitely be of great help. You will find the basics of Oracle explained with simple examples for your understanding. Types of questions covered in this article: Let’s start with 1st article in the series.
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