This document lists 120 top PL/SQL interview questions covering topics such as SQL query execution order, differences between functions and procedures, triggers, collections, joins, exceptions, and performance tuning. The questions range from basic to advanced levels and cover a wide variety of PL/SQL concepts and capabilities.

1. TOP PL/SQL INTERVIEW QUESTIONS
AUTHOR :-ASHWANI PANDEY

2. 1.How sql query gets executed?(order of execution of select
query).
2.What is difference between translate and replace?
3.what is difference between rank and dense rank?
4.what is difference between procedure and function?
5.can we commit inside a trigger?

3. 6.How to commit inside a trigger?
7.what is for update in pl/sql?
8. what is difference in FOR and FOR ALL loop in pl/sql?
9.what is difference between Package and procedure?
10.what is pragma_Init exception?

4. 11.what is pragma autonomous transaction?
12.How to get 3rd highest salary of an employee?
13.how to get department wise highest salary?
14.what is difference between view and materialized view?
15. what are different refresh options for materialized view?

5. 16.what is sql loader and different components of sql loader.
17. what is difference between primary key and unique key?
18. What is control file ,Bad File and discard file?
19.what are the different constraints in a table?
20. what are the type of indexes?

6. 21.what are different type of collection?
22.what is difference between index by table and nested table and varray?
23. what is bulk collect?
24. what are the attributes of bulk collect?
25. what is hierarchical query?

7. 26. what is decode and case and what is difference?
27. how to change rows value into column values in sql?
28.what is cursor and why we need cursors?
29.what are the attributes of cursor?
30.what are the exceptions related to cursor?

8. 31.what is ref cursor?
32.what is context switching in oracle sql pl/sql?
33.what are the different types of triggers?
34.what will be the output for count(*),count(1),count(NULL);
35. what is difference between correlated subquery and inner query?

9. 36.what are different types of joins?
37. what is mutating table error?
38. what is deadlock in oracle?
39.what is difference between implicit and explicit cursor?
40.what are user defined exception?
41.what is RAISE_APPLICATION_ERROR?
42. what is sequence and its attribute in SQL?

10. 43. what is the use of NOCOPY in sql?
44.what is WHERE CURRENT OF in pl/sql?
45. what is result cache in SQL?
46.what is difference between ROWID and ROWNUM?
47.what will be the output of rownum=10,rownum<10,rownum>10;
48.what is difference between truncate and delete and drop?
49.what is referential integrity?
50.What is performance tuning?

11. 51. what is EXPLAIN_PLAN and how it works?
52. what is difference between full table scan and index scan?
53.when no_data_found exception will occur?
54. what is difference between cost based optimization and rule based
optimization and modes of those?
55. what is FlashBack query?
56.What is Compiler Hint and why it is used?
57.What is the difference between union and union all?
58.what is difference between right outer,left outer and full outer join?
59.what will be the difference in output of "select sysdate from dual" and "select
sysdate from employee"?
60.What is Dual table?

12. 61.Can we do update delete or insert in dual table?
62.what is difference between any and all?
63.How to get TOP 2 records or bottom 2 records?
64.How to create an empty table using other table?(using select)
65.how to insert update and delete using select statement?
66.What kind of views can be updated?
67.How to refresh materialized view?
68.what is the use of savepoint,commit and rollback?
69.what are the different steps for query optimization?
70. what is the use of GROUP_BY function?

13. 71.what is difference between where clause and having clause?
72.what are different aggregate functions?
73.what are different date functions in sql?
74.what are different analytical functions in sql?
75.what are different string functions in sql?
76.what is difference between NVL and NVL2?
77.How to get list of all the objects,tables,columns,indexes,constraints
in oracle database?
78.what are DCL,DDL and DML commands?
79.What are different normalization form?
80.What is difference between OLAP and OLTP?

14. 81.what is difference between primary key and unique key with NOT NULL
constraints?
82.what are different logical and arithmetic operators in sql?
83.in two transactions if one of the transaction fails other should get committed,
how to achieve this?
84.what is difference between cast and convert?
85.how to delete duplicate records from table?
86.what is use of cascade constraints?
87.what is record in sql?
88.what is the maximum number of triggers can be applied to a table?(12)
89.what is the use of external tables?
90.what is pl/sql table?

15. 91.what is SQLCODE and SQLERRM?
92.What are the components of a PL/SQL Block?
93.What is difference between % TYPE and % ROWTYPE?
94.What are two virtual tables available during database trigger
execution?:old and :new
95.can we have multiple return statements inside a function?
96.What is Overloading of procedures?
97.What is difference between a Cursor declared in a procedure and
Cursor declared in a package specification?
98.what is the use of UTL_FILE?
99.what is the use of wrap in sql?
100.what is the use of EXECUTE_IMMIDIATE?

16. 101.what are Predefined Exceptions in oracle?
102.What are the various types of parameter modes in a procedure?
103.Can two functions have same name & input parameters but differ only by
return datatype?
104.What is the advantage of a stored procedure over a database trigger ?
105.What is the maximum no.of statements that can be specified in a trigger
statement ?
106.What are cascading triggers? What is the maximum no of cascading triggers
at a time?
107.What are mutating triggers ?
108.Describe Oracle database's physical and logical structure ?
109.What is the use of Control files IN ORACLE ?(POINTER TO DATA FILE)
110.What is the use of Data Dictionary ?

17. 111.what is self referential integrity?
112.What is the maximum no.of columns a table can have ?
113.What is the significance of the & and && operators in PL SQL ?
114.Are views automatically gets updated when base tables are updated ?
115.Is Sysdate a system variable or a system function?
116.How to reverse string without using string function in sql?
117.How to update a rows with opposite gender in SQL?
118.what is the difference between char varchar2 and nvarchar2?
119.what is difference between row level trigger and statement level trigger?
120.how to know the last executed procedure?