删除特定行 - SQLite答案

【问题标题】：Deleting specific rows - SQLite删除特定行 - SQLite
【发布时间】：2019-12-20 04:34:19
【问题描述】：

我正在尝试使用 cte 从与外科医生姓名“Lucille Torres”关联的表“exchange_transactions”中删除重复行。 transaction_id 列应该是唯一的，但在这种情况下是重复的，因此尝试删除它们。我尝试了这段代码，但它似乎不起作用。将 'DELETE' 替换为 'SELECT *' 会显示我想要删除的所有行。我做错了什么？

WITH cte AS (
    SELECT 
        transaction_id,
        surgeon,  
        ROW_NUMBER() OVER (
            PARTITION BY 
                transaction_id
        ) row_num
        FROM exchange_transactions)
DELETE FROM cte
WHERE surgeon = 'Lucille Torres' AND row_num > 1

【问题讨论】：

标签： sql sqlite common-table-expression sql-delete dbeaver

【解决方案1】：

使用ROWID 列获取您不会删除的每个transaction_id 的最小值：

delete from exchange_transactions
where surgeon = 'Lucille Torres'
and exists (
  select 1 from exchange_transactions t
  where t.surgeon = exchange_transactions.surgeon
    and t.transaction_id = exchange_transactions.transaction_id 
    and t.rowid < exchange_transactions.rowid
)

【讨论】：

【解决方案2】：

直接从 CTE 中删除在 SqLite 中不起作用。

但如果该表有一个主键（例如id）
然后可以在删除中使用 CTE 的结果。

例如：

WITH CTE_DUPS AS
(
  SELECT id,
  ROW_NUMBER() OVER (
      PARTITION BY surgeon, transaction_id
      ORDER BY id) AS rn
  FROM exchange_transactions
  WHERE surgeon = 'Lucille Torres'
)
DELETE 
FROM exchange_transactions
WHERE id IN (select id from CTE_DUPS where rn > 1)

测试 dbfiddle here

【讨论】：