Virtual Galaxy Infotech Plsql Developer Interview Questions and Answers

Oracle pl sql developer

Q1. CREATE A FUNCTION BASED ONLOGIC SHARED
Ans. 
Create a function based on shared logic
• Identify common logic that can be reused in multiple functions

• Create a separate function to encapsulate the shared logic

• Call the shared function from other functions where the logic is needed
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Q2. FOR AN ENTITY GIVE DTAILS OF PREVOUS AND NEXT DATE FOR PARTICULAR DEPATMENT
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Q1. Window Functions in SQL
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Window functions in SQL are used to perform calculations across a set of table rows related to the current row.
• Window functions are used to calculate values based on a set of rows related to the current row.

• They allow you to perform calculations without grouping the rows into a single output row.

• Examples of window functions include ROW_NUMBER(), RANK(), and LAG().
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Q1. Uses of Packages in PL/SQL
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Packages in PL/SQL are used to group related procedures, functions, variables, and other PL/SQL constructs together for better organization and security.
• Packages help in modularizing code for easier maintenance and debugging

• They provide encapsulation and hide implementation details

• Packages can contain multiple procedures, functions, variables, cursors, and exceptions

• They improve performance by reducing network traffic

• E...read more
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Q1. EXPLAIN ABOUT UR PRJECT
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Developed a PL/SQL project for managing inventory and sales data in a retail store.
• Designed database tables to store product information, sales transactions, and customer details.

• Implemented PL/SQL procedures and functions for adding, updating, and querying data.

• Created triggers to enforce business rules and maintain data integrity.

• Developed reports using PL/SQL queries to analyze sales performance and inventory levels
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Q2. How do you work on performance optimization
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I work on performance optimization by analyzing query execution plans, indexing, and code refactoring.
• Analyzing query execution plans to identify bottlenecks

• Creating appropriate indexes to improve query performance

• Refactoring code to optimize resource usage

• Using tools like Explain Plan and SQL Tuning Advisor
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Q1. Factorial of a number
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Factorial of a number is the product of all positive integers up to that number.
• To calculate factorial of a number, multiply all positive integers up to that number.

• Factorial of 0 is 1.

• Example: Factorial of 5 is 5*4*3*2*1 = 120.
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Q2. Sql queries including 2nd highest salary and table joins
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Q1. Sql question and table joins
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Q2. Modelling of schema
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Modelling of schema involves designing the structure of a database to organize and represent data.
• Identify entities and their relationships

• Define attributes for each entity

• Establish primary and foreign keys

• Normalize the schema to reduce redundancy

• Consider performance and scalability
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Q1. Plsql and Oracle SQL
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Q1. Discussion for salary
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Q1. What is temp table and temp variable in plsql?
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Temp table is a table created temporarily in memory. Temp variable is a variable that holds temporary data.
• Temp table is used to store data temporarily during a session

• Temp variable is used to hold temporary data that is not needed after a certain point

• Temp table and variable are created using the 'CREATE GLOBAL TEMPORARY' and 'DECLARE' statements respectively

• Example: CREATE GLOBAL TEMPORARY TABLE temp_table (id NUMBER...read more
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Q2. What is mutating table or mutating trigger?
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A mutating table or mutating trigger occurs when a trigger tries to update a table that is currently being modified.
• Mutating table occurs when a trigger references the table that is being modified.

• It can happen when a trigger is fired by an INSERT, UPDATE, or DELETE statement on the table.

• This can lead to unpredictable results or errors, such as ORA-04091: table is mutating, trigger/function may not see it.

• To avoid mut...read more
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Q3. What is autonomous transaction?
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Autonomous transaction is a separate transaction initiated by a parent transaction.
• It allows a subtransaction to commit or rollback independently of the parent transaction.

• It is useful for logging or auditing purposes.

• It can be created using the PRAGMA AUTONOMOUS_TRANSACTION statement.

• Example: A parent transaction updates a table, while an autonomous transaction logs the changes made.

• Example: An autonomous transaction ...read more
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Q4. Cursors definition and types explained
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Cursors are used to retrieve and manipulate data from a database in PL/SQL.
• Cursors are like pointers to a result set, allowing us to fetch and process rows one by one.

• There are two types of cursors: implicit and explicit.

• Implicit cursors are automatically created by Oracle when executing a SQL statement.

• Explicit cursors are declared and used by the programmer.

• Explicit cursors provide more control and flexibility compar...read more
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Q5. Explain about Triggers ?
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Triggers are database objects that automatically execute in response to certain events.
• Triggers can be used to enforce business rules, audit data changes, and maintain referential integrity.

• They can be defined to execute before or after an event, such as a row being inserted, updated, or deleted.

• Triggers can also be nested, meaning one trigger can execute another trigger.

• Examples of triggers include automatically updat...read more
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Q6. Truncate vs delete difference?
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Truncate removes all data, delete removes selected data.
• Truncate is faster than delete as it doesn't log individual row deletions.

• Truncate cannot be rolled back, delete can be.

• Truncate resets identity columns, delete doesn't.

• Truncate doesn't fire triggers, delete does.

• Truncate is a DDL operation, delete is a DML operation.
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Q7. A plsql programme to print 103,99,96...3?
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Q8. What is procedure in plsql and it's syntax and difference between procedure and function?
Ans. 
A procedure in PL/SQL is a named block of code that can be called and executed multiple times.
• Syntax: CREATE [OR REPLACE] PROCEDURE procedure_name [(parameter1 [mode1] datatype1 [, parameter2 [mode2] datatype2]...)] IS

• Difference between procedure and function: Procedures do not return a value, while functions return a value.

• Procedures are used to perform an action, while functions are used to calculate and return a val...read more
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Q1. What are your salary expectations?
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Q2. Share details of your previous job.
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Q3. Tell me about yourself.
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Q4. How do you find if two table having similer data
Ans. 
To find if two tables have similar data, compare the records in both tables using a join or a subquery.
• Use a join operation to compare the records in both tables based on a common column.

• If the tables have a primary key, you can join them on that key to check for similar data.

• Alternatively, you can use a subquery to compare the data in both tables and check for matching records.

• Consider using the MINUS operator to find...read more
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Q5. Difference between having and group by?
Ans. 
HAVING is used to filter groups while GROUP BY is used to group rows based on a column.
• HAVING is used with GROUP BY to filter groups based on a condition

• GROUP BY is used to group rows based on a column

• HAVING is used after GROUP BY in a query

• GROUP BY is used before HAVING in a query

• Example: SELECT department, AVG(salary) FROM employees GROUP BY department HAVING AVG(salary) > 5000;
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