There are "51" Excellent Oracle interview Questions to help you make the new concepts, you are learning as an interview Purpose. It's really very most important:
1.What is Oracle?
Ans-Oracle is a company. Oracle is also a database server, which manages data in a very structured way. It allows users to store and retrieve related data in a multiuser environment so that many users can concurrently access the same data. All this is accomplished while delivering high performance.
A database server also prevents unauthorized access and provides
efficient solutions for failure recovery.
2.What is Database?
Ans-A database is an organized collection of structured information, or data, typically stored electronically in a computer system. A database is usually controlled by a database management system (DBMS). Together, the data and the
DBMS, along with the applications that are associated with them, are referred to as a database system, often shortened to the just database.
Data within the most common types of databases in operation today is typically modeled in rows and columns in a series of tables to make processing and data querying efficient. The data can then be easily accessed, managed, modified, updated,
controlled, and organized. Most databases use structured query language (SQL) for writing and querying data.
3.What is an Oracle table?
Ans-A table is a basic unit of data storage in the Oracle database. A table contains
all the accessible information of a user in rows and columns.
4.What is the relationship between the database, tablespace, and data file?
Ans-An Oracle database contains one or more logical storage units called tablespaces.
These tablespaces collectively store whole data of databases and each tablespace in Oracle database consists of one or more files called datafiles. These datafiles are
the physical structure that confirms with the operating system in which Oracle is running.
5.What is the difference between a hot backup and a cold backup in Oracle? Tell about their benefits also.
Ans-Hot backup (Online Backup): A hot backup is also known as an online backup because it is done while the database is active. Some sites can not shut down their database
while making a backup copy, they are used 24 hours a day, 7 days a week.
Cold backup (Offline Backup): A cold backup is also known as an offline backup because
it is done while the database has been shut down using the SHUTDOWN normal command.
If the database is suddenly shutdown with an uncertain condition it should be
restarted with RESTRICT mode and then shut down with the NORMAL option.
For a complete cold backup, the following files must be backed up.
All datafiles, All control files, All online redo log files(optional), and the init.ora
file (you can recreate it manually).
6.How many memory layers are in the Oracle shared pool?
Ans-Oracle shared pools contains two layers:
1.library cache
2.data dictionary cache
7.What is the save point in the Oracle database?
Ans-Save points are used to divide a transaction into smaller parts. It allows the rolling back of a transaction. A maximum of five save points are allowed. It is used to save our
data, whenever you encounter an error you can roll back from the point where you save your SAVEPOINT.
8.What are the various Oracle database objects?
Ans-
1.Tables: This is a set of elements organized in a vertical and horizontal fashion.
2.Tablespaces: This is a logical storage unit in Oracle.
3.Views: It is a virtual table derived from one or more tables.
4.Indexes: This is a performance tuning method to process the records.
9.What types of joins are used in writing SUBQUERIES?
Ans-
1.Self join
2.Outer Join
3.Equi-join
10.What are the different types of synonyms?
Ans-There are two types of synonyms or alias:
1.Private: It can only be accessed by the owner.
2.Public: It can be accessed by any database user.
11.What is the meaning of recursive hints in Oracle?
Ans-The number of times a dictionary table is repeatedly called by various processes is known as a recursive hint. The recursive hint occurs because
of the small size of the data dictionary cache.
12.What are the limitations of the CHECK constraint?
Ans-The main limitation of CHECK constraint is that the condition must be
a Boolean expression evaluated using the values in the row being inserted
or updated and can't contain subqueries.
13. What is the use of ignoring option in IMP command?
Ans-The IGNORE option is used to specify how an object
creation errors should be handled.
14.What is the use of the SHOW option in IMP command?
Ans-The SHOW option specifies when the value of show=y, the
DDL within the export file is displayed.
15. What are the actual and formal parameters?
Ans-Actual Parameters: Actual parameters are the variables or
expressions referenced in the parameter list of a subprogram.
Let's see a procedure call which lists two
actual parameters named empno and amt:
raise_sal(empno, amt);
Formal Parameters: Formal parameters are variables declared in
a subprogram specification and referenced in the subprogram body.
The following procedure declares two formal parameters named empid and amt:
PROCEDURE raise_sal(empid INTEGER, amt REAL) IS current_salary REAL;
16. How do you find the current date and time in Oracle?
Ans-The SYSDATE() function is used in Oracle to find the current
date and time of operating system on which the database is running.
SELECT TO_CHAR (SYSDATE, 'MM-DD-YYYY HH24:MI: SS') "Current_Date" FROM DUAL;
17. What Is Mirrored On-line Redo Log?
Ans-A mirrored on-line redo log consists of copies of on-line redo log files physically
located on separate disks, changes made to one
members of the group are made to all members.
18. What Are The Different Type Of Segments?
Ans-The different type of Segments are:
1.Data Segment,
2.Index Segment,
3.Rollback Segment and
4.Temporary Segment.
19.What Are Clusters?
Ans-Clusters are groups of one or more tables physically stores
together to share common columns and are often used together.
20.How To Define Data Block Size?
Ans-A data block size is specified for each ORACLE database when the database is created. Database users and allocated free database space in ORACLE data blocks. Block size is specified in INIT.ORA file and can’t be changed later.
21.What Does A Control File Contain?
Ans-A Control file records the physical structure of the database. It contains the following information.
1.Database Name
2.Names and locations of a database's files and redo log files.
3.Time stamp of database creation.
22.What Is the Difference Between Unique Constraint And Primary Key Constraint?
Ans-A column defined as UNIQUE can contain Nulls while a
a column defined as PRIMARY KEY can't contain Nulls.
23.What Is a Distributed Database?
Ans-A distributed database is a network of databases managed by multiple database servers that appears to a user as a single logical database. The data
of all databases in the distributed database can be simultaneously accessed and modified.
24.How Can We Reduce The Network Traffic?
Ans-Replication of data in a distributed environment.
1.Using snapshots to replicate data.
2.Using remote procedure calls.
25.Differentiate Simple And Complex, Snapshots?
An ans-A simple snapshot is based on a query that does not contains GROUP BY
clauses, CONNECT BY clauses, JOINs, sub-query, or snapshot of operations.
Complex snapshots contain at least any one of the above.
26.What Are The Vbx Controls?
Ans-Vbx control provides a simple method of building and enhancing user interfaces.
The controls can use to obtain user inputs and display program outputs.vbx control
where originally develop as extensions for the ms visual basic environments and
include such items as sliders, ridges, and knobs.
27.What Is The Use Of Transactional Triggers?
Ans-Using transactional triggers we can control or modify the default functionality of the oracle forms.
28.What Is The Basic Data Structure That Is Required For Creating An Lov?
Ans-Record Group.
29.What Is The Maximum Allowed Length Of Record Group Column?
Ans-Record group column names cannot exceed 30 characters.
30.Which Parameter Can Be Used To Set Read Level Consistency Across Multiple Queries?
Ans-Read only
31.What Are The Different Types Of Record Groups?
Ans-The different types of Record Groups are:
1.Query Record Groups
2.NonQuery Record Groups
3.State Record Groups.
32.What Is An Index?
Ans-An Index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. The index can be created on one or more columns of a table.
33.What Is An Extent?
Ans-An Extent is a specific number of contiguous data blocks, obtained
in a single allocation, and used to store a specific type of information.
34.What Is A View?
Ans-A view is a virtual table. Every view has a Query attached to it.
(The Query is a SELECT statement that identifies the
columns and rows of the table(s) the view uses.)
35.What Are The Advantages Of Views?
Ans-Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.
Hide data complexity.
Simplify commands for the user.
Present the data in a different perspective from that of the base table.
Store complex queries.
36.What Is Lexical Reference? How Can It Be Created?
Ans-Lexical reference is place_holder for a text that can be embedded in a SQL statement.
A lexical reference can be created using & before the column or parameter name.
37.What Is System.coordination_operation?
Ans-It is a terminal screen with the internal state of the form. It updates
the screen display to reflect the information that oracle forms have
in its internal representation of the screen.
38.What Use Of Command Line Parameter Cmd File?
Ans-It is a command-line argument that allows you to
specify a file that contains a set of arguments for r20run.
39.What Are The Built-ins Used For Creating And Deleting Groups?
Ans- CREATE-GROUP (function)
CREATE_GROUP_FROM_QUERY(function)
DELETE_GROUP(procedure)
40.What Are Different Types Of Canvas Views?
Ans- 1.Content canvas views
2.Stacked canvas views
3.Horizontal toolbar
4.vertical toolbar.
41.What Are The Different Types Of Delete Details We Can Establish In Master-details?
Ans- 1.Cascade
2.Isolate
3.Non-isolate
42.What Is Relation Between The Window And Canvas Views?
Ans-Canvas views are the background objects on which you place the interface
items (Text items), checkboxes, radio groups, etc.,) and boilerplate objects
(boxes, lines, images, etc.,) that operators interact with us they run your form.
Each canvas views displayed in a window.
43.What Is A User_exit?
Ans-Calls the user exit named in the user_exit_string. Invokes a 3Gl
program by name which has been properly linked into your
current oracle forms executable.
44.What is the USING Clause and give example?
Ans-The USING clause is used to specify with the column to
test for equality when two tables are joined.
[sql]select * from employee to join salary using employee ID[/sql]
Employee tables join with the Salary tables with the Employee ID.
45.What is a subquery and what are the different types of subqueries?
Ans-Sub Query is also called a Nested Query or Inner Query which is used to get data from multiple tables. A subquery is added in the
where clause of the main query.
There are two different types of subqueries:
1.Correlated subquery
A Correlated subquery cannot be as independent query but can reference
a column in a table listed in the list of the outer query.
2.Non-Correlated subquery
This can be evaluated as if it were an independent query. Results of the
a subquery is submitted to the main query or parent query.
46.What is cross join?
Ans-Cross join is defined as the Cartesian product of records from the tables present in the join. The cross join will produce a result which
combines each row from the first table with each row from the second table.
47.What are temporal data types in Oracle?
Ans-Oracle provides the following temporal data types:
1.Date Data Type – Different formats of Dates
2.TimeStamp Data Type – Different formats of Time Stamp
3.Interval Data Type – Interval between dates and time
48.What is the difference between rename and alias?
Ans-Rename is a permanent name given to a table or a column
whereas Alias is a temporary name given to a table or column.
Rename is nothing but a replacement of name and Alias is an
the alternate name of the table or column.
49.What is the data type of the DUAL table?
Ans-The DUAL table is a one-column table present in the oracle database.
The table has a single VARCHAR2(1) column called DUMMY which has a value of ‘X’.
50.What is the difference between Cartesian Join and Cross Join?
Ans-There are no differences between the join. Cartesian and Cross join are the same.
Cross join gives the cartesian product of two tables – Rows from the first table is multiplied
with another table which is called cartesian product.
Cross join without where clause gives the Cartesian product.
51.What are the differences between LOV and List Item?
Ans-LOV is property whereas list items are considered as single items.
The list of items is set to be a collection of lists of items. A list item
can have only one column, LOV can have one or more columns.
Conclusion-In this tutorial you will have to learn Oracle Excellent
top "51" famous Interview question and Answer
So I hope you liked these tutorials. If you have any questions or
suggestions related to Oracle interview purpose
please comment below and let us know.
Finally, if you find this post informative, then share it
with your friends on Facebook, Twitter, Instagram.
Thank you...
Comments
Post a Comment