SELECT t.id as id, substring_index(substring_index(t.str,',', b.help_topic_id + 1), ',', -1) as str
FROM tba t join mysql.help_topic b ON b.help_topic_id < (LENGTH(t.str) - LENGTH(REPLACE(t.str, ',', '')) + 1);

参考：http://blog.csdn.net/ldl22847/article/details/47609727

跪求大神帮忙。急急急急。

 CREATE DEFINER=`root`@`localhost` PROCEDURE `split`(in _string varchar(300))  
BEGIN  
# 求分割符号','的位置  
declare _index int;  

#使用临时表存储分割后的结果  
drop temporary table if exists tmp_strs;  
create temporary table tmp_strs(  
str int(10) unsigned  
);  

set _index = locate(',',_string);  
while _index > 0  
do  
insert into tmp_strs values(left(_string,_index-1));#将子字符串存入临时表  
set _string =substr(_string from _index+1);  
set _index = locate(',',_string);  
end while;  

if length(_string) >= 0 then  
insert into tmp_strs values(_string);  
end if;  

END