Question

我有这个查询检查从搜索文本框输入的每个关键字，并且必须返回最匹配的关键字。我已经使查询和它的工作正常。问题是，我想在返回的行中排除所有带有0值的KW_MATCHED。

   SELECT
    A1.*, (
        SELECT
            sum(
                CASE
                WHEN (A1.ID = A2.tag_id)
                AND (
                    A2.keyword = 'keyword1' || A2.keyword = 'keyword2'
                ) THEN
                    1
                ELSE
                    0
                END
            )
        FROM
            tbl_article_tags A2
    ) AS KW_MATCHED
FROM
    tbl_article A1
ORDER BY
    KW_MATCHED DESC

结果：

+----+---------------+----------------+------------+
| ID | Title         | Content        | KW_MATCHED |
+----+---------------+----------------+------------+
| 1  | title         | Lorem Ipsum... | 7          |
+----+---------------+----------------+------------+
| 2  | another title | Lorem Ipsum... | 5          |
+----+---------------+----------------+------------+
| 3  | another title | Lorem Ipsum... | 0          |
+----+---------------+----------------+------------+
| 4  | another title | Lorem Ipsum... | 0          |
+----+---------------+----------------+------------+

我尝试重新使用Alias KW_MATCHED作为WHERE子句（请参阅下面的查询），但它会返回以下消息：

[Err] 1054 - 未知列＆＃39; KW_MATCHED＆＃39;在＆＃39; where子句＆＃39;

SELECT
    A1.*, (
        SELECT
            sum(
                CASE
                WHEN (A1.ID = A2.tag_id)
                AND (
                    A2.keyword = 'keyword1' || A2.keyword = 'keyword2'
                ) THEN
                    1
                ELSE
                    0
                END
            )
        FROM
            tbl_article_tags A2
    ) AS KW_MATCHED
FROM
    tbl_article A1
WHERE
    KW_MATCHED > 0
ORDER BY
    KW_MATCHED DESC

有什么办法吗？谢谢你的先进和对不起我的坏英语：）

Answer 1

尝试使用HAVING而不是WHERE

SELECT
A1.*, 
(SELECT sum(case when (A1.ID=A2.tag_id) AND (A2.keyword='keyword1' || A2.keyword='keyword2') then 1 else 0 end) FROM tbl_article_tags A2) as KW_MATCHED
FROM tbl_article A1
HAVING KW_MATCHED > 0
ORDER BY KW_MATCHED DESC

MySql重用WHERE子句的别名

1 个答案: