view of weekly data

Hi, friend,

Suppose there is table of daily transaction data with 5 fields,

time(date), open(float8), high(float8), low(float8), close(float8)

Is it possible to create a view of weekly data, i.e. open is the first day'open, high is the highest of the week, low
isthe lowest of the week, close is the last day's close. 

Thank you.