MySQL - 长文本字段的词频计数

Question

我有一个MySQL 表，其中一个字段包含文本描述（约 5-200 个字）。

例如Reviews:

Rev_id    Place_id    Stars    Category    Text
1         12           3        Food       Nice food but a bad dirty place.
2         31           4        Sport      Not bad, they have everything.
3         55           1        Bar        Poor place,bad audience.

我想做一些字数分析，例如一般字频计数（每个单词出现了多少次）或每个类别的前 K 个单词。

在示例中：

word    count
bad     3
place   2
...

有没有办法只在MySQL 中做到这一点而不涉及编程语言？

Answer 1

我对这个问题的逻辑是：提取所有单词并计算它们！

因此，创建一个类似于您存储的数据的表：

CREATE TABLE `tbltest` (
  `Rev_id` int(11) NOT NULL AUTO_INCREMENT,
  `place_id` int(11) DEFAULT NULL,
  `Stars` int(11) DEFAULT NULL,
  `Category` varchar(45) DEFAULT NULL,
  `Text` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`Rev_id`),
  UNIQUE KEY `id_UNIQUE` (`Rev_id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

并为单词创建一个表格：

CREATE TABLE `counting` (
  `word` varchar(45) NOT NULL,
  `counts` int(11) DEFAULT NULL,
  PRIMARY KEY (`word`),
  UNIQUE KEY `word_UNIQUE` (`word`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

现在，创建MySQL Stored Procedure 用于拆分句子和计算单词：

drop procedure if exists sentence_words;
delimiter #
create procedure sentence_words(IN Cat VARCHAR(45))

begin

declare w_max int unsigned default 1;
declare w_counter int unsigned default 0;
declare done int unsigned default 0;

declare sentence varchar(255) default null;
declare cur cursor for select `text` from `tbltest` where `Category` = Cat;
declare continue handler for not found set done=1;
set done=0;
open cur;
    myloop: loop
        fetch cur into sentence;
        if done = 1 then leave myloop; end if;
        -- refine sentence!
        set sentence = replace(replace(replace(replace(
                sentence
        ,'.',' '),'!',' '),',',' '),';',' ');
        set sentence = replace(trim(sentence),'  ',' ');
        set w_max = length(sentence)-length(replace(sentence,' ',''))+1;
        start transaction;
        while w_counter < w_max do
            insert into `counting`(counts,word) values
                (1, substring_index( substring_index(
                    sentence,' ',w_counter+1) ,' ',-1)
                )
            ON DUPLICATE KEY UPDATE counts=counts+1;
            set w_counter=w_counter+1;
        end while;
        commit;
    end loop;
    close cur;
end #
delimiter ;

最后，您可以调用该过程并在counting 表中查找单词和计数。如果您需要将每个类别的字数分开，请记住在为每个类别调用过程之前将truncate 或备份counting 表。

truncate `counting`;
call sentence_words('Bar');
select * from `counting` order by counts desc; -- ? where length(word)>2
-- words | counts --
'audience', '1'
'bad', '1'
'place', '1'
'Poor', '1'