SQLite3 无法删除行，没有这样的列错误

Question

我有一个简单的 sqlite 数据库设置，其中有一个名为 sightings 的 table 和一个名为 name 的 table 列。我可以运行正常 SELECT 查询和插入和更新就好了，但是当我尝试运行删除时，它会在我给它的列中添加 "new." 然后说它不存在：

sqlite> DELETE FROM sightings WHERE name = "blah";
Error: no such column: new.name
sqlite> DELETE FROM sightings WHERE names = "blah";
Error: no such column: names

该列名为 "name"，当我 select 该列时，它会在其前面添加 "new."，但是当我 select 一个错误的列时，它不会't exist ("names" 如上)，它只是说它通常不存在，没有 "new."。如有任何帮助，我们将不胜感激。

Answer 1

您似乎有一个 DELETE TRIGGER，并且该 TRIGGER 错误地使用 new.name 来引用已删除行的名称列（对于 DELETE TRIGGER old.is用于引用已删除行中的列）。

您应该将 TRIGGER 更改为使用 old.name 而不是 new.name.

new.column 仅适用于 INSERT 或 UPDATE 触发器。
old.column 仅适用于 DELETE 或 UPDATE 触发器。

根据 :-

Both the WHEN clause and the trigger actions may access elements of the row being inserted, deleted or updated using references of the form "NEW.column-name" and "OLD.column-name", where column-name is the name of a column from the table that the trigger is associated with. OLD and NEW references may only be used in triggers on events for which they are relevant, as follows:

INSERT NEW references are valid

UPDATE NEW and OLD references are valid

DELETE OLD references are valid

SQL As Understood By SQLite - CREATE TRIGGER

也许考虑下面的例子:-

CREATE TABLE IF NOT EXISTS sightings (name TEXT);
CREATE TABLE IF NOT EXISTS deleted_sightings (name TEXT); /* Table to be populated by the trigger */
INSERT INTO sightings VALUES ('blah'),('notblah'),('anothernotblah');
/* Normal deletion without triggers */
DELETE FROM sightings WHERE name = 'blah';
SELECT * FROM sightings; /* RESULT 1 (sightings table after deletion)*/

/* Add the row that was deleted again */
INSERT INTO sightings VALUES('blah');

/* Add a valid AFTER DELETE TRIGGER referring to the old column */
/* The Trigger will add a row to the deleted_sightings table using the value from the deleted row */
CREATE TRIGGER IF NOT EXISTS correct_trigger 
    AFTER DELETE ON sightings 
    BEGIN INSERT INTO deleted_sightings 
        VALUES(old.name); 
    END;
DELETE FROM sightings WHERE name = 'blah';
SELECT * FROM sightings; /* RESULT 2 (sightings table after deletion)*/
SELECT * FROM deleted_sightings; /* RESULT 3  deleted_sightings table */

/* Add a Trigger that will try to add a row to the deleted_sightings table */
/* BUT will result in the new.name column not being found as there is no */
/* new. for a DELETE trigger only old. */
CREATE TRIGGER IF NOT EXISTS incorrect_trigger AFTER DELETE ON sightings BEGIN INSERT INTO deleted_sightings VALUES(new.name); END;
/* Show the triggers */
SELECT * FROM sqlite_master WHERE type = 'trigger'; /* RESULT 4 - The triggers as per sqlite_master */
DELETE FROM sightings WHERE name = 'blah'; /* <<<<< DELETE will fail due to incorrect trigger */

结果是：-

以及由于不正确的触发器导致的错误：-

/* RESULT 4 - The triggers as per sqlite_master */
DELETE FROM sightings WHERE name = 'blah'
> no such column: new.name
> Time: 0s

SQLite3 无法删除行，没有这样的列错误

SQLite3 can't DELETE row, no such column Error

sqlite

new-operator

delete-row

sql-delete