T-sql IF Condition date evaluation - tsql

Question

I have a simple question regarding T-SQL. I have a stored procedure which calls a Function which returns a date. I want to use an IF condition to compare todays date with the Functions returned date. IF true to return data.
Any ideas on the best way to handle this. I am learning t-sql at the moment and I am more familar with logical conditions from using C#.
ALTER FUNCTION [dbo].[monday_new_period](#p_date as datetime) -- Parameter to find current date
RETURNS datetime
BEGIN
-- 1 find the year and period given the current date
-- create parameters to store period and year of given date
declare #p_date_period int, #p_date_period_year int
-- assign the values to the period and year parameters
select
#p_date_period=period,
#p_date_period_year = [year]
from client_week_uk where #p_date between start_dt and end_dt
-- 2 determine the first monday given the period and year, by adding days to the first day of the period
-- this only works on the assumption a period lasts a least one week
-- create parameter to store the first day of the period
declare #p_start_date_for_period_x datetime
select #p_start_date_for_period_x = min(start_dt)
from client_week_uk where period = #p_date_period and [year] = #p_date_period_year
-- create parameter to store result
declare #p_result datetime
-- add x days to the first day to get a monday
select #p_result = dateadd(d,
case datename(dw, #p_start_date_for_period_x)
when 'Monday' then 0
when 'Tuesday' then 6
when 'Wednesday' then 5
when 'Thursday' then 4
when 'Friday' then 3
when 'Saturday' then 2
when 'Sunday' then 1 end,
#p_start_date_for_period_x)
Return #p_result
END
ALTER PROCEDURE [dbo].[usp_data_to_retrieve]
-- Add the parameters for the stored procedure here
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
IF monday_new_period(dbo.trimdate(getutcdate()) = getutcdate()
BEGIN
-- SQL GOES HERE --
END
Thanks!!

Answer 1

I assume you are working on Sql2008. See documentation of IF and CASE keywords for more details.
CREATE FUNCTION dbo.GetSomeDate()
RETURNS datetime
AS
BEGIN
RETURN '2012-03-05 13:12:14'
END
GO
IF CAST(GETDATE() AS DATE) = CAST(dbo.GetSomeDate() AS DATE)
BEGIN
PRINT 'The same date'
END
ELSE
BEGIN
PRINT 'Different dates'
END
-- in the select query
SELECT CASE WHEN CAST(GETDATE() AS DATE) = CAST(dbo.GetSomeDate() AS DATE) THEN 1 ELSE 0 END AS IsTheSame

Answer 2

This is the basic syntax for a T-SQL IF and a date compare.
If you are comparing just the date portion for equality you will need to use:
select dateadd(dd,0, datediff(dd,0, getDate()))
This snippet will effectively set the time portion to 00:00:00 so you can compare just dates. So in use it will look something like this.
IF dateadd(dd,0, datediff(dd,0, fn_yourFunction())) = dateadd(dd,0, datediff(dd,0, GETDATE()))
BEGIN
RETURN SELECT * FROM SOMEDATA
END
Hope that helps!