.SQL Server中 image类型数据的比较

IF object_id(‘compare_image‘) IS NOT NULL DROP FUNCTION compare_image
GO
create function compare_image(@a1 image, @a2 image) returns int
-- if match, return 1
as
begin
declare @n int, @i int, @j int
declare @b1 varbinary(8000), @b2 varbinary(8000)
set @n = 1
if datalength(@a1) <> datalength(@a2) -- different length
set @n = 0
else
begin
set @i = 0
set @j = (datalength(@a1) - 1) / 8000 + 1
while @i <= @j
begin
set @b1 = substring(@a1, @i * 8000 + 1, case @i when @j then datalength(@a1) % 8000 else 8000 end)
set @b2 = substring(@a2, @i * 8000 + 1, case @i when @j then datalength(@a2) % 8000 else 8000 end)
if @b1 <> @b2
begin
set @n = 0
break
end 
set @i = @i + 1
end 
end
return(@n)
end
go