HCL Group Plsql Developer Interview Questions and Answers

Q1. What is groupby
Ans. 
The GROUP BY clause in SQL is used to group rows that have the same values into summary rows.
• It is used with aggregate functions like COUNT, SUM, AVG, etc.

• It is used to group rows based on one or more columns in a table.

• It is often used in conjunction with the SELECT statement.
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Q2. What is having
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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. What is view? Can we update in view?
Ans. 
A view is a virtual table created by a query. It does not store data itself but displays data from one or more tables. Views can be used for querying data as if it were a table.
• Views are created using a SELECT statement with optional joins, WHERE clauses, etc.

• Views can simplify complex queries by pre-defining joins and filters.

• Views do not store data themselves, they display data from underlying tables.

• Views can be upd...read more
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Q2. What is synonym?
Ans. 
A synonym is an alternative name for a table, view, sequence, or other database object.
• Synonyms can be used to provide a different name for an object, making it easier to reference.

• They can be created to reference objects in other schemas or databases.

• Synonyms can be public (accessible to all users) or private (accessible only to the creator).
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Q3. What is sequence
Ans. 
A sequence is a database object in Oracle that generates unique numbers in a specified order.
• Used to generate unique numbers for primary key columns

• Can be used in INSERT statements to automatically generate values

• Can be defined to increment by a specific value and start at a specific number
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Q4. What is procedures?
Ans. 
Procedures are named PL/SQL blocks that perform a specific task. They can accept parameters and return values.
• Procedures are stored in the database and can be called by other PL/SQL blocks or applications.

• They can accept input parameters to perform operations and can also return output values.

• Procedures help in modularizing code and promoting reusability.

• Example: CREATE PROCEDURE calculate_salary (emp_id IN NUMBER) IS
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Q5. What is difference between procedure and functions
Ans. 
Procedures do not return any value while functions return a value.
• Procedures are used to perform an action, while functions are used to calculate and return a value.

• Procedures do not have a return statement, while functions must have a return statement.

• Functions can be called from SQL queries, while procedures cannot be called directly in SQL queries.
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Q6. What is partitions?
Ans. 
Partitions in PL/SQL are used to divide a table into smaller, more manageable pieces.
• Partitions help improve query performance by allowing data to be stored in separate segments based on a specified criteria.

• Common partitioning methods include range, hash, list, and composite partitioning.

• Example: Partitioning a sales table by month can improve query performance when searching for sales data within a specific time fram
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Q1. 1.How to search a text in all database objects- search in all_source table 2.difference between procedure & function 3.difference between case & decode 4.write a query to delete duplicates from table 5.whi...read more
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Q1. Waiting for round 1 results
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It is little bit easy

2 coding question in python

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
Ans. 
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. Triggers , procedures , exception handling , collections, package
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Q2. Type , array, partition, performance tuning, AWR
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Q1. What is the difference between SQL and PL/SQL?
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Q2. How can distinct values be obtained without using the DISTINCT keyword?
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