mysql sql语法中的单词计数 [英] mysql count word in sql syntax
本文介绍了mysql sql语法中的单词计数的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
让我们进行一个简单的查询:
Lets have a simple query:
SELECT myfield
FROM mytable
WHERE criteria
例如,上面的查询为我们提供了10行结果.字段myField
是文本字段.
The above query gives us 10 rows of results for example. The field myField
is a text field.
我的问题是:是否可以更改上述查询并获得myField
字段的总字数?
My question is this: is it possible to alter the above query and get the total word count of the myField
field?
已编辑:总字数"是指查询中所有行中所有选定字段的总字数
Edited: By total word count I mean the total word count of all selected fields in query, in all rows
示例
+------------------------------+-------+
| sentence | Words |
+------------------------------+-------+
| Hello World | 2 |
| Hello World | 2 |
| Mary had a little lamb | 5 |
| Her fleece was white as snow | 6 |
| Everywhere that mary went | 4 |
| Umm, sheep followed her | 4 |
+------------------------------+-------+
推荐答案
Use the excellent function from this question by @otis in your query:
mysql> select * from test;
+----+------------------------------+
| id | sentence |
+----+------------------------------+
| 0 | Hello World |
| 1 | Hello World |
| 2 | Mary had a little lamb |
| 3 | Her fleece was white as snow |
| 4 | Everywhere that mary went |
| 5 | Umm, sheep followed her |
+----+------------------------------+
6 rows in set (0.00 sec)
mysql> SELECT sentence, wordcount(sentence) as "Words" from test;
+------------------------------+-------+
| sentence | Words |
+------------------------------+-------+
| Hello World | 2 |
| Hello World | 2 |
| Mary had a little lamb | 5 |
| Her fleece was white as snow | 6 |
| Everywhere that mary went | 4 |
| Umm, sheep followed her | 4 |
+------------------------------+-------+
6 rows in set (0.02 sec)
要使函数正常工作,您需要在MySQL中执行函数的声明.就像执行任何其他查询一样:
To make the function work, you need to execute the declaration of the function in MySQL. It is just like executing any other query:
mysql> DELIMITER $$
mysql> CREATE FUNCTION wordcount(str TEXT)
RETURNS INT
DETERMINISTIC
SQL SECURITY INVOKER
NO SQL
BEGIN
DECLARE wordCnt, idx, maxIdx INT DEFAULT 0;
DECLARE currChar, prevChar BOOL DEFAULT 0;
SET maxIdx=char_length(str);
WHILE idx < maxIdx DO
SET currChar=SUBSTRING(str, idx, 1) RLIKE '[[:alnum:]]';
IF NOT prevChar AND currChar THEN
SET wordCnt=wordCnt+1;
END IF;
SET prevChar=currChar;
SET idx=idx+1;
END WHILE;
RETURN wordCnt;
END
$$
Query OK, 0 rows affected (0.10 sec)
mysql> DELIMITER ;
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