datename function in sql

Question

I wanted to get the week from the given date, for this I tried with the DATENAME function to get the WEEK like,

 Select DateName(WEEK,'2012-03-09')

am getting the output as 10. I want to get the starting date and ending date of this week like, 2012-03-04 to 2012-03-10 Is it possible?

Answer 1

Do something like this:

DECLARE @MyDate Date = '2012-03-09';

-- This gets you the SUNDAY of the week your date falls in...
SELECT DATEADD(DAY, -(DATEPART(WEEKDAY, @MyDate) - 1), @MyDate);

-- This gets you the SATURDAY of the week your date falls in...
SELECT DATEADD(DAY, (7 - DATEPART(WEEKDAY, @MyDate)), @MyDate);

-- This will show the range as a single column
SELECT
  CONVERT(NVarChar, DATEADD(DAY, -(DATEPART(WEEKDAY, @MyDate) - 1), @MyDate))
  + ' through ' +
  CONVERT(NVarChar, DATEADD(DAY, (7 - DATEPART(WEEKDAY, @MyDate)), @MyDate));

Answer 2

try the following, change getdate to your date

Select 
DateAdd(d, 1- DatePart(dw,GetDate()),GetDate()) FirstDayOfWeek,
DateAdd(d, 7- DatePart(dw,GetDate()),GetDate()) LastDayOfWeek

Answer 3

This does not rely on your default setting of datefirst.

set datefirst 4 -- this row does nothing in this query. 
                -- It will hurt the queries using datepart though
declare @t table(dt datetime)
insert @t values('2012-03-09 11:12'), ('2012-03-10 11:12'),('2012-03-11 11:12')

-- week from sunday to saturday 
Select dateadd(week, datediff(week, 0, dt),-1),
       dateadd(week, datediff(week, 0, dt),+5)
from @t