sql 返回 第几周

--孕妇预产期 周数
/****** 对象:  UserDefinedFunction [dbo].[f_crm_getedcweek]    脚本日期: 07/27/2020 17:24:52 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER FUNCTION [dbo].[f_crm_getedcweek](@edc datetime)
RETURNS int
AS
BEGIN
    
	declare @edcweek int,@today datetime,@ledc datetime
    set @edcweek = 0
    set @today = convert(char(10),getdate(),126)
    if @edc >= @today
    begin
		set @ledc = @edc - 280;
        set @edcweek =   abs(datediff(day,@today,@ledc)  / 7);
       
    end




RETURN @edcweek
END

　　

----返回星期名字
ALTER FUNCTION [dbo].[f_pre_getweekname](@date datetime,@weekname varchar(10) = '',@flag int = 0)
RETURNS varchar(10)
AS
BEGIN
declare @weekid int
declare @myweekname varchar(10)
if @flag = 0
begin
set @weekid = DATEPART(w,@date);
if @weekid = 7 set @myweekname = '星期六'
else if @weekid = 1 set @myweekname = '星期天'
else if @weekid = 2 set @myweekname = '星期一'
else if @weekid = 3 set @myweekname = '星期二'
else if @weekid = 4 set @myweekname = '星期三'
else if @weekid = 5 set @myweekname = '星期四'
else if @weekid = 6 set @myweekname = '星期五'
end
else if @flag = 1
begin
if @weekname = '星期六' set @weekid = 7
else if @weekname = '星期天' set @weekid = 1
else if @weekname = '星期一' set @weekid = 2
else if @weekname = '星期二' set @weekid = 3
else if @weekname = '星期三' set @weekid = 4
else if @weekname = '星期四' set @weekid = 5
else if @weekname = '星期五' set @weekid = 6
end 

if @flag = 1 set @myweekname = cast(@weekid as varchar(10))
return @myweekname

END