WEEK(), WEEKOFYEAR()
WEEK(), WEEKOFYEAR() — Returns the week of the year as an integer value.
Synopsis
WEEKOFYEAR(   timestamp-value   ) 
Description
The WEEK() and WEEKOFYEAR() functions are synonyms and return an
    integer value between 1 and 52 representing the timestamp's week of the
    year. These functions produce the same result as using the WEEK_OF_YEAR
    keyword with the EXTRACT() fucntion.
Examples
The following example uses the WEEK() function to group and sort
    records containing a timestamp.