SQL Statement - Nesting Functions

Single-row functions can be nested to any depth. Nested functions are evaluated from the innermost level to the outermost level. Some examples follow to show you the flexibility of these functions.

SELECT last_name,
FROM   employees
WHERE  department_id = 60;

The example displays the last names of employees in department 60. The evaluation of the SQL statement involves three steps:

1.       The inner function retrieves the first eight characters of the last name.
Result1 = SUBSTR (LAST_NAME, 1, 8)

2.       The outer function concatenates the result with _US.
Result2 = CONCAT(Result1, '_US')

3.       The outermost function converts the results to uppercase.
The entire expression becomes the column heading because no column alias was given.

Display the date of the next Friday that is six months from the hire date. The resulting date should appear as Friday, August 13th, 1999. Order the results by hire date.
         (hire_date, 6), 'FRIDAY'),
         'fmDay, Month ddth, YYYY')
         "Next 6 Month Review"
FROM      employees
ORDER BY  hire_date;