Telecall Technology Application Support Engineer Interview Questions and Answers

To fetch the second highest salary in SQL, use subqueries or the DISTINCT keyword with ORDER BY and LIMIT.

• Use a subquery: SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees);

• Use DISTINCT: SELECT DISTINCT salary FROM employees ORDER BY salary DESC LIMIT 1 OFFSET 1;

• Use ROW_NUMBER() function: SELECT salary FROM (SELECT salary, ROW_NUMBER() OVER (ORDER BY salary DESC) AS rank FROM employ...read more

A shell script to print even numbers within a specified range.

• Use a for loop to iterate through a range of numbers.

• Check if a number is even using the modulus operator (%).

• Print the number if it is even.

• Example: for i in {1..10}; do if [ $((i % 2)) -eq 0 ]; then echo $i; fi; done

Use tools like grep, find, and log files to locate error patterns in Linux files.

• Use 'grep' to search for patterns: `grep 'error_pattern' /path/to/files/*`.

• Combine 'find' with 'grep' to search recursively: `find /path/to/dir -type f -exec grep -H 'error_pattern' {} \;`.

• Check log files in '/var/log/' for application-specific errors, e.g., `cat /var/log/syslog | grep 'error_pattern'`.

• Use 'tail' to monitor log files in re...read more

Use the 'find' command to locate files older than 10 days in Linux.

• Use the command: find /path/to/directory -type f -mtime +10

• The '-type f' option specifies that we are looking for files.

• The '-mtime +10' option finds files modified more than 10 days ago.

• To list files in a specific directory, replace '/path/to/directory' with the actual path.

• You can also use '-ls' to list details: find /path/to/directory -type f -mtime ...read more

Use SQL queries to identify and fetch duplicate records based on specific columns.

• Use the GROUP BY clause to group records by the column(s) you want to check for duplicates.

• Utilize the HAVING clause to filter groups that have a count greater than 1.

• Example: SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name HAVING COUNT(*) > 1;

• You can fetch all columns of duplicate records by joining the result with t...read more

Use the 'find' command to locate files larger than 10GB in a specified directory.

• Use the command: find /path/to/directory -type f -size +10G

• Replace '/path/to/directory' with the actual directory you want to search.

• The '-type f' option ensures only files are considered, not directories.

• The '+10G' specifies files larger than 10 gigabytes.

Use 'sed' command in Unix to search and replace patterns in files efficiently.

• Use 'sed' command: `sed -i 's/old_pattern/new_pattern/g' filename`

• The '-i' option edits the file in place.

• The 's' command stands for substitute.

• The 'g' flag at the end replaces all occurrences in the line.

Stored procedures are precompiled SQL statements that can be executed to perform operations on a database.

• Syntax: CREATE PROCEDURE procedure_name AS SQL_statement;

• Example: CREATE PROCEDURE GetEmployee AS SELECT * FROM Employees;

• Parameters can be added: CREATE PROCEDURE GetEmployeeByID @ID INT AS SELECT * FROM Employees WHERE EmployeeID = @ID;

• Stored procedures can return values: CREATE PROCEDURE GetTotalEmployees AS RET...read more

RDBMS stands for Relational Database Management System, which organizes data into tables for easy access and management.

• Data is stored in tables (e.g., MySQL, PostgreSQL).

• Supports SQL (Structured Query Language) for querying data.

• Ensures data integrity through constraints (e.g., primary keys, foreign keys).

• Allows relationships between tables (e.g., one-to-many, many-to-many).

• Examples include Oracle, Microsoft SQL Serve...read more

Views are virtual tables; materialized views store data physically for faster access.

• A view is a virtual table based on a SQL query, while a materialized view stores the result set physically.

• Views are updated dynamically with the underlying data changes; materialized views require manual refresh to update.

• Example of a view: SELECT * FROM employees WHERE department = 'Sales';

• Example of a materialized view: CREATE MATER...read more

SQL query to find Nth highest salary, fetch duplicate records, and shell script for Fibonacci series.

• To find Nth highest salary in SQL, use the 'ROW_NUMBER()' function with 'ORDER BY' and 'LIMIT'. Example: SELECT salary FROM (SELECT salary, ROW_NUMBER() OVER (ORDER BY salary DESC) AS rn FROM employees) AS temp WHERE rn = N;

• To fetch duplicate records in SQL, use the 'GROUP BY' and 'HAVING' clauses. Example: SELECT colum...read more

Dense rank function assigns a rank to each row within a partition of a result set, with no gaps in the ranking values.

• Use the DENSE_RANK() function in SQL to assign a unique rank to each row within a partition

• It is similar to the RANK() function but does not leave gaps in the ranking values

• Example: SELECT column1, DENSE_RANK() OVER (PARTITION BY column2 ORDER BY column3) AS dense_rank FROM table_name

The HAVING clause is used in SQL to filter groups based on a specified condition.

• HAVING clause is used with the GROUP BY clause to filter groups based on a specified condition

• It is used to filter the results after grouping has been done

• It is similar to the WHERE clause but operates on grouped records

Using a for loop to fetch the Fibonacci series.

• Initialize variables for the first two numbers in the series (0 and 1).

• Use a for loop to calculate the next number in the series by adding the previous two numbers.

• Store each number in the series in an array.

• Continue the loop until reaching the desired length of the series.

A shell script to check system health

• Check CPU usage using 'top' or 'ps' command

• Check memory usage using 'free' or 'top' command

• Check disk usage using 'df' command

• Check network connectivity using 'ping' command

• Check system load using 'uptime' command

• Check running processes using 'ps' command

The highest salary in SQL can vary depending on factors such as location, experience, and industry.

• The highest salary in SQL is typically found in roles such as database administrators, data engineers, and data architects.

• Factors that can influence the highest salary include the candidate's level of experience, the location of the job, and the industry.

• For example, a senior database administrator in a major tech hub li...read more

To delete duplicate records in SQL, you can use the DELETE statement with a subquery.

• Identify the duplicate records using a SELECT statement with GROUP BY and HAVING clause.

• Create a subquery to select the duplicate records.

• Use the DELETE statement with the subquery to delete the duplicate records.

Grep command is used in Unix to search for specific patterns in files.

• Grep stands for Global Regular Expression Print.

• It is a powerful command-line tool for searching text files.

• It uses regular expressions to match patterns.

• Grep can search for patterns in a single file or multiple files.

• It can also search recursively in directories.

• Grep has various options to control the search behavior.

• Some common options include -i (...read more

Awk command in Unix is a powerful text processing tool used for extracting and manipulating data.

• Awk command is used for pattern scanning and processing of text files.

• It allows you to specify patterns and actions to be performed on those patterns.

• Awk operates on a line-by-line basis, processing one line at a time.

• It can be used to extract specific columns from a file, perform calculations, and generate reports.

• Awk uses...read more