基于Edit：
描述列可以包含任意长度的文本（LONGTEXT）
以下查询应适用于LONGTEXT。

INSERT INTO words
SELECT DISTINCT REGEXP_REPLACE(TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(description, ' ', numbers.n), ' ', -1)), '[^[:alnum:]]', '') AS word
FROM
  (SELECT @row := @row + 1 AS n FROM (SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5) t1,
  (SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5) t2,
  (SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5) t3,
  (SELECT @row:=0) t4) numbers
  INNER JOIN products
  ON CHAR_LENGTH(description) - CHAR_LENGTH(REPLACE(description, ' ', '')) >= numbers.n - 1;

这是DBFIDDLE Demo。
上述代码还应删除任何逗号、引号、连字符、分号和其他特殊字符，然后才能将单个单词插入表中。
如果您对表格中的重复条目（单词）没有问题;然后在查询开始时删除distinct子句。

CREATE TABLE products (
    product VARCHAR(255),
    description LONGTEXT
    );

INSERT INTO products (product, description) VALUES 
('apple', 'yummy green fruit'),
('banana', 'nutritional yellow fruit');

SELECT DISTINCT word
FROM products
CROSS JOIN JSON_TABLE(
    CONCAT('["', REPLACE(description, ' ', '","'), '"]'),
    '$[*]' COLUMNS (
        word VARCHAR(255) PATH '$'
        )
    ) jsontable

fiddle