Sqlite：以編程方式創建觸發器

Question

當我的應用程序第一次安裝時，我以編程方式創建數據庫。迄今爲止工作良好。但是當我想添加一個觸發器時，我得到一個異常說「IF附近的語法錯誤」。問題是，我無法跨越源代碼中多行的字符串。那我能做些什麼呢？

private void createTriggers(SQLiteDatabase database) { 

    final String triggerLocationArchived = "CREATE TRIGGER location_archived AFTER UPDATE ON location FOR EACH ROW BEGIN IF NEW.deleted <> OLD.deleted THEN UPDATE sector set sector.deleted = NEW.deleted WHERE sector.location = NEW._id; END IF; END;"; 

    database.execSQL(triggerLocationArchived); 
} 

有兩個表：位置和扇區。每個都有一個INTEGER標誌，指示該行是否已被歸檔。所以我希望所有的孩子（一個地點內的部門）都歸檔，如果父母（地點）歸檔。

Answer 1

試試這個命令：

CREATE TRIGGER location_archived 
AFTER UPDATE ON location 
FOR EACH ROW 
WHEN NEW.deleted <> OLD.deleted 
BEGIN 
    UPDATE sector 
    set deleted = NEW.deleted 
    WHERE location = NEW._id; 
END 

您的代碼將是這樣的：

private void createTriggers(SQLiteDatabase database) { 

    final String triggerLocationArchived = "CREATE TRIGGER location_archived AFTER UPDATE ON [location] FOR EACH ROW WHEN NEW.deleted <> OLD.deleted BEGIN UPDATE sector set deleted = NEW.deleted WHERE location = NEW._id; END"; 

    database.execSQL(triggerLocationArchived); 
}