SQLServer向MySQL移植笔记(一)自定义函数

这个是我在移植数据库后，从SQL Server移植过来的。对于SQL大侠们，这个算是毛毛雨了。
SQL Server2000的自定义函数如下：

CREATE FUNCTION getfiletype (@kuozhanming varchar(100))
RETURNS varchar(100)
AS
BEGIN
declare @filetype varchar(100)
declare @index int

set @filetype=''
if (@kuozhanming is null and @kuozhanming = '')
select @filetype = ''


else
begin
SET @kuozhanming = Reverse(@kuozhanming)
SELECT @index = charindex('.',@kuozhanming)
if (@index < 2)
select @filetype = ''
else
begin
SET @kuozhanming = left(@kuozhanming,@index - 1)
SET @kuozhanming = Reverse(@kuozhanming)

SET @kuozhanming = Lower(@kuozhanming)


SELECT @filetype =
CASE( @kuozhanming)
WHEN 'doc' THEN 'application/msword'
WHEN 'log' THEN 'application/octet-stream'
WHEN 'ini' THEN 'application/octet-stream'
WHEN 'exe' THEN 'application/octet-stream'
WHEN 'dll' THEN 'application/octet-stream'
WHEN 'rar' THEN 'application/octet-stream'
WHEN 'txt' THEN 'text/html'
WHEN 'html' THEN 'text/html'
WHEN 'htt' THEN 'text/html'

WHEN 'bmp' THEN 'image/bmp'
WHEN 'jpg' THEN 'image/pjpeg'
WHEN 'avi' THEN 'video/avi'
else @kuozhanming
end
end
end

return @filetype
END

MySQL实现相同功能的的自定义函数如下
drop function if exists getfiletype;
DELIMITER |

/*
取出文件名中扩展名的文件名称
比如
c:/1234/5678.txt
则返回 txt对应的 text/html;
*/
CREATE FUNCTION getfiletype (t_kuozhanming varchar(100))
RETURNS varchar(100)
BEGIN
declare t_filetype varchar(100);
declare t_index int;

set t_filetype='';
if (t_kuozhanming is null or t_kuozhanming = '') then
set t_filetype = '';
else
SET t_kuozhanming = Reverse(t_kuozhanming);
SET t_index = locate('.',t_kuozhanming) ;
if (t_index < 2) then
set t_filetype = '';
else
SET t_kuozhanming = left(t_kuozhanming,t_index - 1);
SET t_kuozhanming = Reverse(t_kuozhanming);
SET t_kuozhanming = Lower(t_kuozhanming);
SELECT CASE( t_kuozhanming)
WHEN 'doc' THEN 'application/msword'
WHEN 'log' THEN 'application/octet-stream'
WHEN 'ini' THEN 'application/octet-stream'
WHEN 'exe' THEN 'application/octet-stream'
WHEN 'dll' THEN 'application/octet-stream'
WHEN 'rar' THEN 'application/octet-stream'
WHEN 'txt' THEN 'text/html'
WHEN 'html' THEN 'text/html'
WHEN 'htt' THEN 'text/html'

WHEN 'bmp' THEN 'image/bmp'
WHEN 'jpg' THEN 'image/pjpeg'
WHEN 'avi' THEN 'video/avi'
else t_kuozhanming
end into t_filetype;
end if;
end if;

return t_filetype;

end|
DELIMITER ;