select count(uuid) from a1 group by substring(id,1,6)
可以使用MySQL的SUBSTR函数http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_substr#SUBSTR(str,pos), SUBSTR(str FROM pos), SUBSTR(str,pos,len), SUBSTR(str FROM pos FOR len)SUBSTR() is a synonym for SUBSTRING(). #SUBSTRING(str,pos), SUBSTRING(str FROM pos), SUBSTRING(str,pos,len), SUBSTRING(str FROM pos FOR len)
#SUBSTRING(str,pos), SUBSTRING(str FROM pos), SUBSTRING(str,pos,len), SUBSTRING(str FROM pos FOR len)