Write a SQL statement using employees table to display the first name column, the index value if letter n is contained/found in first name, the first name after replacing n with *, and the first name after deleting n in its beginning or ending.

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Write a SQL statement using employees table to display the 3^rd of a salary, the 3^rd of a salary rounded with no decimal part, and the 3^rd of a salary truncated with no decimal part.

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Considering that all employees are still working in the company, write a SQL statement using employees table to display the first name, date hired, the number of days he/she is employed, and the number of years he/she is employed.

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database(oracle)