在MySQL中删除关系位置的记录？

我试图清理存储在MySQL表中的记录。如果一行包含%X%，我需要删除该行及其下一行，而不考虑内容。例如，对不起，如果桌子侮辱了任何人的智力：

| 1 | leave alone 
| 2 | Contains %X% - Delete
| 3 | This row should also be deleted
| 4 | leave alone
| 5 | Contains %X% - Delete
| 6 | This row should also be deleted
| 7 | leave alone

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有没有一种方法可以只用几个查询就可以做到这一点？或者我必须首先使用%x%搜索参数执行SELECT查询，然后循环这些结果并执行DELETE…对于返回的每个索引+1，在单个查询中没有合理的方法来执行此操作。这是可能的，但最终不得不使用的查询将非常复杂，并且几乎肯定无法移植到其他SQL引擎

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使用您在问题中描述的先选择后删除的方法。

这应该是可行的，尽管它有点笨重，可能需要检查LIKE参数，因为它使用模式匹配。请参见注释 从table.db中删除 idcol在哪里 从db.table中选择idcol，其中的col类似于“%X%” 还是艾德科林

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从db.table中选择idcol+1，其中col`LIKE'%X%'

假设该表名为test，包含在名为id和data的列中

我们从一个SELECT开始，它为我们提供所有行的id，这些行的前一行id最高，低于当前行的id：

SELECT t1.id FROM test t1
  JOIN test t2 ON
    ( t2.id, true )
      =
    ( SELECT t3.id, t3.data LIKE '%X%' FROM test t3
        WHERE t3.id < t1.id ORDER BY id DESC LIMIT 1 )

这给了我们3，6，2，5-很好

现在，我们不能从表中删除，也不能从MySQL中的同一个表中选择-因此，让我们使用一个临时表，将要删除的ID存储在其中，然后从该临时表中读取以从原始表中删除：

CREATE TEMPORARY TABLE deleteids (id INT);

INSERT INTO deleteids
  (SELECT t1.id FROM test t1
    JOIN test t2 ON
      ( t2.id, true )
        =
      ( SELECT t3.id, t3.data LIKE '%X%' FROM test t3
          WHERE t3.id < t1.id ORDER BY id DESC LIMIT 1 )
  )
  UNION
  (
    SELECT id FROM test WHERE data LIKE '%X%'
  );

  DELETE FROM test WHERE id in (SELECT * FROM deleteids);

。。。我们的测试表中只剩下ID 1、4和7

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由于前面的行是使用选择的，所以您可以在一个DELETE语句中完成所有操作：

假设紧随其后的行基于基于INT的ID列的顺序，则可以使用MySQL变量来分配行号，该行号可以解释ID中的间隔：

DELETE a FROM tbl a
JOIN (
    SELECT a.id, b.id AS nextid
    FROM (
        SELECT     a.id, a.text, @rn:=@rn+1 AS rownum 
        FROM       tbl a
        CROSS JOIN (SELECT @rn:=1) rn_init
        ORDER BY   a.id
    ) a
    LEFT JOIN (
        SELECT     a.id, @rn2:=@rn2+1 AS rownum 
        FROM       tbl a
        CROSS JOIN (SELECT @rn2:=0) rn_init
        ORDER BY   a.id
    ) b ON a.rownum = b.rownum
    WHERE a.text LIKE '%X%'
) b ON a.id IN (b.id, b.nextid)

它首先获取数据并根据ID列对其进行排序，然后在几乎相同的结果集上执行偏移左连接，只是排名列落后1。这将并排获取行及其紧邻的下一行，以便我们可以在父DELETE语句中同时提取它们的两个id：

SELECT a.id, a.text, b.id AS nextid, b.text AS nexttext
FROM (
    SELECT     a.id, a.text, @rn:=@rn+1 AS rownum 
    FROM       tbl a
    CROSS JOIN (SELECT @rn:=1) rn_init
    ORDER BY   a.id
) a
LEFT JOIN (
    SELECT     a.id, a.text, @rn2:=@rn2+1 AS rownum 
    FROM       tbl a
    CROSS JOIN (SELECT @rn2:=0) rn_init
    ORDER BY   a.id
) b ON a.rownum = b.rownum
WHERE a.text LIKE '%X%'

收益率：

ID     | TEXT                   | NEXTID   | NEXTTEXT
2      | Contains %X% - Delete  | 3        | This row should also be deleted
5      | Contains %X% - Delete  | 6        | This row should also be deleted
257    | Contains %X% - Delete  | 3434     | This row should also be deleted
4000   | Contains %X% - Delete  | 4005     | Contains %X% - Delete
4005   | Contains %X% - Delete  | 6000     | Contains %X% - Delete
6000   | Contains %X% - Delete  | 6534     | This row should also be deleted

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然后，在删除ID为子选定ID或NEXTID的行的条件下，我们加入-删除整个语句。

@Aiias:这是一个完全不同的问题。这依赖于ID中的非间隙。LIKE不使用regexes，REGEXP使用；看见

ID     | TEXT                   | NEXTID   | NEXTTEXT
2      | Contains %X% - Delete  | 3        | This row should also be deleted
5      | Contains %X% - Delete  | 6        | This row should also be deleted
257    | Contains %X% - Delete  | 3434     | This row should also be deleted
4000   | Contains %X% - Delete  | 4005     | Contains %X% - Delete
4005   | Contains %X% - Delete  | 6000     | Contains %X% - Delete
6000   | Contains %X% - Delete  | 6534     | This row should also be deleted