如何在 SQLite 上使用 CTE 和更新/删除?

2022-01-17 00:00:00 sql-update sql common-table-expression sqlite

SQLite 现在有 CTE，文档 说您可以将它用于插入、更新和删除查询——但是仅给出 select 语句的示例.

SQLite now has CTEs, and the documentation says you can use it with insert, update and delete queries -- but only gives examples of select statements.

我可以通过 insert-select 弄清楚 CTE 如何应用于插入；但是我们如何在没有 from 子句的更新或删除中使用它们?

I can figure out how CTEs apply to inserts, via insert-select; but how can we use them in update or delete, where there is no from-clause?

推荐答案

可以在子查询中使用 CTE:

CTEs can be used in subqueries:

WITH NewNames(ID, Name) AS (...)
UPDATE MyTable
SET Name = (SELECT Name
            FROM NewNames
            WHERE ID = MyTable.ID);

WITH IDsToDelete AS (...)
DELETE FROM MyTable
WHERE ID IN IDsToDelete;

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