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
Ans. 
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. Self introduction and questions related to my project
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Q2. What are joins in SQL, and can you provide examples of their usage?
Ans. 
Joins in SQL are used to combine rows from two or more tables based on a related column between them.
• Joins are used to retrieve data from multiple tables based on a related column.

• Common types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

• Example: SELECT * FROM table1 INNER JOIN table2 ON table1.column = table2.column;
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Q3. What are the built-in functions available in SQL?
Ans. 
Some built-in functions in SQL include AVG, COUNT, MAX, MIN, SUM, and CONCAT.
• AVG: Calculates the average value of a numeric column

• COUNT: Counts the number of rows in a result set

• MAX: Returns the maximum value in a column

• MIN: Returns the minimum value in a column

• SUM: Calculates the sum of values in a column

• CONCAT: Concatenates two or more strings together
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Q4. What are the different types of cursors in database management systems?
Ans. 
Types of cursors in database management systems include implicit, explicit, and parameterized cursors.
• Implicit cursors are automatically created by the database when a SQL statement is executed.

• Explicit cursors are defined by the programmer and give more control over the result set.

• Parameterized cursors allow for dynamic SQL statements with parameters.

• Examples: SELECT statement using implicit cursor, DECLARE, OPEN, FET...read more
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Q5. What is the difference between procedures and functions in programming?
Ans. 
Procedures are used to perform an action, while functions return a value.
• Procedures do not return a value, while functions do.

• Functions can be used in SQL queries, while procedures cannot.

• Functions can be called from within SQL statements, while procedures cannot.

• Procedures can have OUT parameters to return multiple values, while functions can only return a single value.
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Q6. What is the query to print the third highest salary from the given table?
Ans. 
Use a subquery to find the third highest salary in a table.
• Use the RANK() function to assign a rank to each salary in descending order.

• Filter the results to only include rows with a rank of 3.

• Consider handling ties in salaries appropriately.
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Q7. What is a package, and how do you utilize it in your project?
Ans. 
A package is a collection of related procedures, functions, variables, and other PL/SQL constructs.
• Packages help organize and encapsulate code for easier maintenance and reuse.

• They can contain both public and private elements.

• Packages can be used to group related functionality together, improving code modularity.

• Example: CREATE PACKAGE my_package AS ... END my_package;
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Q8. Can you describe two complex JIRA issues you have worked on?
Ans. 
Resolved a critical bug causing data loss and implemented a new feature for better user experience.
• Identified root cause of data loss bug by analyzing database queries and logs

• Collaborated with cross-functional teams to prioritize and implement a fix

• Designed and implemented a new feature based on user feedback to enhance usability
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Q9. What are the different types of indexes?
Ans. 
Different types of indexes include B-tree, Bitmap, Function-based, and Reverse key indexes.
• B-tree indexes are the most common type and are suitable for most indexing needs.

• Bitmap indexes are used for columns with low cardinality, such as gender or status columns.

• Function-based indexes are created based on expressions or functions applied to columns.

• Reverse key indexes store keys in reverse order to reduce contention in
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Q10. What are analytical functions in sql?
Ans. 
Analytical functions in SQL are used to perform calculations across a set of rows related to the current row.
• Analytical functions operate on a group of rows and return a single result for each row.

• They can be used to calculate running totals, moving averages, rank, percentiles, etc.

• Examples include ROW_NUMBER(), RANK(), DENSE_RANK(), SUM() OVER(), AVG() OVER().
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Q11. What are aggregate functions in SQL?
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Aggregate functions in SQL are functions that operate on a set of values and return a single value as output.
• Aggregate functions include functions like SUM, AVG, COUNT, MIN, and MAX.

• They are used with the GROUP BY clause to perform calculations on groups of rows.

• Examples: SELECT SUM(salary) FROM employees; SELECT AVG(age) FROM students GROUP BY class;
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Q12. How did you handle performance tuning in your project?
Ans. 
I identified and optimized slow-performing SQL queries by analyzing execution plans and indexing strategies.
• Identified slow-performing SQL queries using tools like Oracle SQL Developer or TOAD.

• Analyzed execution plans to understand query performance bottlenecks.

• Optimized queries by rewriting SQL code, adding indexes, or restructuring data.

• Used tools like Explain Plan or SQL Tuning Advisor to improve query performance.

• R...read more
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Q13. What is data modeling?
Ans. 
Data modeling is the process of creating a visual representation of data structures and relationships within a database.
• Data modeling helps in organizing and understanding complex data systems.

• It involves identifying entities, attributes, and relationships between them.

• Examples include ER diagrams, UML diagrams, and relational data models.
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Q14. What steps did you take to perform root cause analysis in your project?
Ans. 
I conducted thorough analysis by reviewing code, logs, and discussing with team members.
• Reviewed code to identify potential issues

• Analyzed logs for error messages and patterns

• Discussed with team members to gather insights and perspectives

• Used debugging tools to trace the root cause
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Q15. What is a trigger in database management, and what are its different types?
Ans. 
A trigger in database management is a special type of stored procedure that is automatically executed when certain events occur in a database.
• Triggers can be used to enforce business rules, maintain referential integrity, and automate repetitive tasks.

• There are two main types of triggers: row-level triggers and statement-level triggers.

• Row-level triggers are fired for each row affected by a triggering statement, while ...read more
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Q1. EXPLAIN ABOUT UR PRJECT
Ans. 
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
Ans. 
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
Ans. 
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
Ans. 
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?
Ans. 
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?
Ans. 
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 ?
Ans. 
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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