InfraEn Consulting Safety Officer Interview Questions and Answers

To replace male with female in Oracle, use the UPDATE statement with the SET clause.

• Use the UPDATE statement with the SET clause to replace male with female in Oracle

• Example: UPDATE employees SET gender='female' WHERE gender='male'

• Make sure to specify the table name and column name correctly

• Use WHERE clause to specify the condition for replacement

Query to display 3rd highest salary

• Use the ORDER BY clause to sort the salaries in descending order

• Use the LIMIT clause to limit the result to the third row

• Use a subquery to exclude the top two salaries

Delete removes specific rows while truncate removes all rows from a table.

• Delete is a DML command while truncate is a DDL command.

• Delete is slower than truncate as it logs each row deletion while truncate does not.

• Delete can be rolled back while truncate cannot be rolled back.

• Delete can have a WHERE clause to specify which rows to delete while truncate removes all rows.

• Delete does not reset the identity of the table wh

A cursor is a database object used to manipulate data in a result set.

• A cursor is used to traverse through a result set one row at a time.

• There are two types of cursors: static and dynamic.

• Static cursors are read-only and scroll forward only.

• Dynamic cursors are updatable and can scroll in any direction.

• Cursors can be used in stored procedures, triggers, and functions.

Procedure is a set of instructions that performs a specific task, while function returns a value after performing a task.

• Procedure does not return a value, while function does.

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

• Functions can have parameters passed to them, while procedures can have both parameters and arguments.

• Examples of procedures include printing to the console, while examples ...read more

Display second last line of a file using command line.

• Use the tail command with -n option to display last two lines of the file.

• Then use head command with -n option to display the second last line.

• Example: tail -n 2 file.txt | head -n 1

Command to replace Sam with vam on 5th line

• sed '5s/Sam/vam/' filename.txt

• awk 'NR==5 {sub(/Sam/, "vam")} 1' filename.txt

Command to display blank line in file

• Use echo command with empty quotes to create a blank line in a file

• Syntax: echo '' >> filename

• Alternatively, use printf command with newline character

• Syntax: printf ' ' >> filename

Soft links are pointers to the original file while hard links are additional names for the same file.

• Soft links are created using the 'ln -s' command while hard links are created using the 'ln' command.

• Soft links can point to files on different file systems while hard links cannot.

• Deleting the original file will render a soft link useless while a hard link will still work.

• Soft links have different inode numbers while h...read more

Use the 'du' command to display biggest file on server.

• Open terminal or SSH into server

• Navigate to directory to search from

• Run 'du -a . | sort -n -r | head -n 1' command

• The output will display the biggest file on the server