Question

我有一个包含文章的表，另一个包含文章的行

一旦删除了给定行中的所有文章，我也需要删除该行。

这是我目前的查询

SET @id = :id;
SET @section = 0;
SET @row = 0;
SET @row_id = 0;
SET @count = 0;

SELECT @row := articles.row_order, @section := articles.section_id
FROM articles
WHERE article.article_id = @id;

DELETE FROM articles WHERE article_id = @id;

SELECT @count := COUNT(articles.article_id)
FROM articles
JOIN rowstyles ON articles.section_id = rowstyles.row_section_id 
AND articles.row_order = rowstyles.row_position
WHERE rowstyles.row_section_id = @section AND rowstyles.row_position = @row;

DELETE ...

如果@count为0（零）

，如何删除行（行样式）

Answer 1

您可以将计数添加到DELETE s where子句：

-- Delete rowstyles with no article
DELETE FROM rowstyles WHERE (SELECT COUNT(a.id) FROM articles a WHERE a.section_id = rowstyles.row_section_id) = 0;

请注意，这将删除所有没有文章的行样式。如果它仅用于给定的部分，则可以添加到WHERE子句：

DELETE FROM rowstyles  
WHERE (
    SELECT COUNT(a.article_id) 
    FROM articles a 
    WHERE 
    a.section_id = @section AND a.row_order = @row) = 0 
    AND
    rowstyles.row_section_id = @section AND rowstyles.row_position = @row;

在运行SQL之前，请先确保备份。

MYSQL DELETE WHERE CONDITION（COUNT = 0）

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