ios - 触发自动向另一个表添加记录

Question

我有一张 table :

项目

itemID int autoincrement
itemName text

itemAvailability

itemID       integer REFERENCES Items (itemID)
availability integer DEFAULT 0

我需要一个触发器来做:

当用户将一条记录添加到 Items 表中时，触发器必须自动将一条记录添加到 itemAvailability 表中。

itemAvailability.itemID=元素.itemID

此刻我来到了这一点并卡住了:

CREATE TRIGGER updateItemsAvailabilityTbl AFTER INSERT ON items
BEGIN
INSERT INTO itemAvailability (itemID)
VALUES (items.itemID)
END

嗯，这对我不起作用。请帮忙。

Answer 1

您的 CREATE TRIGGER 语句中有两个错误。 1. 如 documentation 中所写

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

所以你应该写new.itemID而不是items.itemID。 2. INSERT INTO 语句应该以分号结束。试试这个:

CREATE TRIGGER updateItemsAvailabilityTbl AFTER INSERT ON items
BEGIN
INSERT INTO itemAvailability (itemID)
VALUES (new.itemID);
END