数据库存在关键字以“;”隔开,查询的结果集按关键字幅出现的次数降序排列,并按单个关键词在页面展示。以下为存储过程
CREATE PROCEDURE `proc_split`( inputstring varchar(1000), delim char(1) ) NOT DETERMINISTIC CONTAINS SQL SQL SECURITY DEFINER COMMENT '' begin declare strlen int; declare last_index int; declare cur_index int; declare cur_char VARCHAR(200); declare len int; set cur_index=1; set last_index=0; set strlen=length(inputstring); drop temporary table if exists splittable;/**/ create TEMPORARY table splittable( id int AUTO_INCREMENT, value VARCHAR(20), PRIMARY KEY (`ID`), UNIQUE KEY `ID` (`ID`) ) ; WHILE(cur_index<=strlen) DO begin if substring(inputstring from cur_index for 1)=delim or cur_index=strlen then set len=cur_index-last_index-1; if cur_index=strlen then set len=len+1; end if; insert into splittable(`value`)values(substring(inputstring from (last_index+1) for len)); set last_index=cur_index; end if; set cur_index=cur_index+1; END; end while; end /*测试*/ call proc_split('a;b;c;d',';'); select * from splittable;
上面只适合于对单个词做处理,可能我们自己遇到的情况是,将所有的字段(每个字段可能只包含一个关键词,也可能包含多个关键词)处理成一个多关键词处理,附带一个sql可以实现
select group_concat(name separator ';') as tags from tags where LENGTH(name)>0
参数说明:LENGTH(name)>0 是为空的字段不做处理