php - MySQL向列插入重复单词的数量

Question

我有一个包含重复单词的表格和一个名为“num”的空字段。

+----+--------------+-----+
| id | words        | num |
+----+--------------+-----+
| 1  | red          |     |
+----+--------------+-----+
| 2  | blue         |     |
+----+--------------+-----+
| 3  | red          |     |
+----+--------------+-----+
| 4  | red          |     |
+----+--------------+-----+
| 5  | blue         |     |
+----+--------------+-----+

我想像这样在 num 字段中插入重复单词的数量:

+----+--------------+-----+
| id | words        | num |
+----+--------------+-----+
| 1  | red          | 1   |
+----+--------------+-----+
| 2  | blue         | 1   |
+----+--------------+-----+
| 3  | red          | 2   |
+----+--------------+-----+
| 4  | red          | 3   |
+----+--------------+-----+
| 5  | blue         | 2   |
+----+--------------+-----+

我如何通过 php 或 sql 执行此操作？

Answer 1

这适用于 MySQL。

您可以加入一个子查询，它使用相关子查询根据 ID 在每个 words 上生成一个行号。

UPDATE  tableName a
        INNER JOIN
        (
            SELECT  a.id, 
                    (
                        SELECT  COUNT(*)
                        FROM    tableName c
                        WHERE   c.words = a.words AND
                                c.id <= a.id
                    ) AS RowNumber
            FROM    TableName a
        ) b ON a.id = b.id
SET     a.num = b.rownumber

• > SQLFiddle Demo