day 10 函数 引入sqlserver 以外的函数

表值函数  返回一张表

SELECT * FROM sdata.dbo.taobaocar
DROP function dbo.subd_day

use pmart
go
create function dbo.subd_day(@priov varchar(255))
returns table
as

return (select * from sdata.dbo.taobaocar
where priov = @priov)
go

select * from pmart.dbo.subd_day ('贵州')

相减的函数

use pmart
go
create function dbo.subd_day(@date3 varchar(255),@date4 varchar(255))
returns float
as
begin
declare @sum_date int
declare @date3_format date
declare @date4_format date

if @date3='00:00.0' or @date3 = 'NULL' or @date3 is NULL
begin
set @date3='1900-01-01'
end
else
begin
set @date3_format = @date3
end

if @date4='00:00.0' or @date4 = 'NULL' or @date4 is NULL
begin
set @date4='1900-01-01'
end

else
begin
set @date4_format = @date4
end

set @sum_date = DATEDIFF(dd,@date3,@date4)
return @sum_date
end

select dbo.subd_day ('2018-05-12','2018-05-18')

简单取最大的数的函数

drop function dbo.subd_day
use pmart
go
create function dbo.subd_day(@num1 float,@num2 float)
returns float
as
begin
declare @max_num float
if @num1 >@num2
begin
set @max_num=@num1
end

else
begin
set @max_num=@num2
end
return @max_num
end
select dbo.subd_day (22,25)