Oracle PL/ SQL Interview Questions

Interview Questions: Oracle, PL SQL


• What are the different types of joins?
• What is the difference between procedure and function
• What is group by function
• What is the difference between a where clause and having clause
• What are indexes. Advantages of indexes
• Triggers, how many triggers are available
• What does “i” represent in Oracle8i / 9i
• Difference between primary key and foreign key
• Can we have null in a primary key
• Can we have null in a foreign key, if yes , how many in a table
• What are cursors
• Give example of how SQL tuning can be done
• What is normalization
• Difference between delete and truncate
• Are you aware of water level mark in oracle database? What is it?
• What are views, snapshots and synonyms?
• What value one gets for “Select * from dual”
• Have you used Decode function? Give an example
• Example when inner joins was used?
• Example when outer joins was used?
• Datatypes supported by Oracle
• Can you explain how do index retrieve records from database
• What is commit and rollback
• What is the difference between these 2 queries
o Select count(*) from table
o Select count(1) from table
• Difference between NODATAFOUND and %NOFOUND
• Difference between IN and EXISTS? Which is faster in execution?
• What is referential integrity
• What are constraints
• What are transaction isolation levels?
• What are materialized views?