Cascade

Hibernate, automatically persist dependant objects

我怕爱的太早我们不能终老 提交于 2019-12-18 04:55:21
问题 I'm quite new to Hibernate and have been trying to determine what it will do for you and what it requires you to do. A big one is dealing with an object that has dependants that don't yet exist in the database. For example, I have a Project object that includes a Manufacturer field that accepts a Manufacturer object as its value. In the database I have a products table with a mfr_id column that's a reference to the manufacturers table (a fairly typical unidirectional one-to-many relationship)

How can I cast a QVariant to custom class?

牧云@^-^@ 提交于 2019-12-18 03:22:31
问题 I'm developing a BlackBerry 10 mobile application using the Momentics IDE (native SDK). I have a listview which I want to handle its items click with C++ (I need to use C++ not QML). I can get the index path using the "connect" instruction, but I have problem with parsing a QVariant to a custom class ; Q_ASSERT(QObject::connect(list1, SIGNAL(triggered(QVariantList)), this, SLOT(openSheet(QVariantList)))); QVariant selectItem = m_categoriesListDataModel->data(indexPath); I tried to use the

In SQL Server 2005, can I do a cascade delete without setting the property on my tables?

倖福魔咒の 提交于 2019-12-17 21:46:19
问题 I have a database full of customer data. It's so big that it's really cumbersome to operate on, and I'd rather just slim it down to 10% of the customers, which is plenty for development. I have an awful lot of tables and I don't want to alter them all with "ON DELETE CASCADE", especially because this is a one-time deal. Can I do a delete operation that cascades through all my tables without setting them up first? If not, what is my best option? 回答1: Combining your advice and a script I found

基于深度学习的图像分割在高德的实践

怎甘沉沦 提交于 2019-12-17 10:08:48
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 一、前言 图像分割(Image Segmentation)是计算机视觉领域中的一项重要基础技术,是图像理解中的重要一环。图像分割是将数字图像细分为多个图像子区域的过程,通过简化或改变图像的表示形式,让图像能够更加容易被理解。更简单地说,图像分割就是为数字图像中的每一个像素附加标签,使得具有相同标签的像素具有某种共同的视觉特性。 图像分割技术自 60 年代数字图像处理诞生开始便有了研究,随着近年来深度学习研究的逐步深入,图像分割技术也随之有了巨大的发展。早期的图像分割算法不能很好地分割一些具有抽象语义的目标,比如文字、动物、行人、车辆。这是因为早期的图像分割算法基于简单的像素值或一些低层的特征,如边缘、纹理等,人工设计的一些描述很难准确描述这些语义,这一经典问题被称之为“语义鸿沟”。 得益于深度学习能够“自动学习特征”的这一特点,第三代图像分割很好地避免了人工设计特征带来的“语义鸿沟”,从最初只能基于像素值以及低层特征进行分割,到现在能够完成一些根据高层语义的分割需求。 (图像分割的发展历史) 高德地图拥有图像/视频大数据,在众多业务场景上都需要理解图像中的内容。例如,在数据的自动化生产中,通常需要寻找文字、路面、房屋、桥梁、指示牌、路面标线等目标。这些数据里有些是通过采集车辆或卫星拍摄

【2019年8月版】OCP 071认证考试原题-第41题

时光毁灭记忆、已成空白 提交于 2019-12-17 10:08:33
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> choose three The ORDERS table has a primary key constraint on the ORDER_ID column. The ORDER_ITEMS table has a foreign key constraint on the ORDER_ID column,referencing the primary key of the ORDERS table. The constraint is defined with on DELETE CASCADE. There are rows in the ORDERS table with an ORDER_TOTAL less than 1000. Which three DELETE statements execute successfully? A) DELETE FROM orders WHERE order_total<1000; B) DELETE * FROM orders WHERE order_total<1000; C) DELETE orders WHERE order_total<1000; D) DELETE FROM orders; E) DELETE order_id FROM

When/Why to use Cascading in SQL Server?

雨燕双飞 提交于 2019-12-17 02:55:13
问题 When setting up foreign keys in SQL Server, under what circumstances should you have it cascade on delete or update, and what is the reasoning behind it? This probably applies to other databases as well. I'm looking most of all for concrete examples of each scenario, preferably from someone who has used them successfully. 回答1: Summary of what I've seen so far: Some people don't like cascading at all. Cascade Delete Cascade Delete may make sense when the semantics of the relationship can

基于深度学习的图像分割在高德的实践

蹲街弑〆低调 提交于 2019-12-16 11:32:41
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 一、前言 图像分割(Image Segmentation)是计算机视觉领域中的一项重要基础技术,是图像理解中的重要一环。图像分割是将数字图像细分为多个图像子区域的过程,通过简化或改变图像的表示形式,让图像能够更加容易被理解。更简单地说,图像分割就是为数字图像中的每一个像素附加标签,使得具有相同标签的像素具有某种共同的视觉特性。 图像分割技术自 60 年代数字图像处理诞生开始便有了研究,随着近年来深度学习研究的逐步深入,图像分割技术也随之有了巨大的发展。早期的图像分割算法不能很好地分割一些具有抽象语义的目标,比如文字、动物、行人、车辆。这是因为早期的图像分割算法基于简单的像素值或一些低层的特征,如边缘、纹理等,人工设计的一些描述很难准确描述这些语义,这一经典问题被称之为“语义鸿沟”。 得益于深度学习能够“自动学习特征”的这一特点,第三代图像分割很好地避免了人工设计特征带来的“语义鸿沟”,从最初只能基于像素值以及低层特征进行分割,到现在能够完成一些根据高层语义的分割需求。 (图像分割的发展历史) 高德地图拥有图像/视频大数据,在众多业务场景上都需要理解图像中的内容。例如,在数据的自动化生产中,通常需要寻找文字、路面、房屋、桥梁、指示牌、路面标线等目标。这些数据里有些是通过采集车辆或卫星拍摄

On delete cascade - where I have to add it

拜拜、爱过 提交于 2019-12-14 02:47:38
问题 I needed an example of cascade delete. My question is, where do I add it? In the table I create PK, or in other tables where this PK is sitting there as FK? Can I use "alter table" to add "on delete cascade" to existing table? An example please? @edit MYSQL, using phpMyAdmin @edit 2 Does it look good? alter table wplaty drop foreign key pesel, add constraint pesel foreign key (pesel) references baza_osob(pesel) on delete cascade on update restrict; My parent table = baza_osob My child table =

How to add persisted entities in a relationship marked with CascadeType.ALL?

做~自己de王妃 提交于 2019-12-13 19:26:09
问题 I have an Entity with a bidirectional ManyToMany relationship (on the same entity) marked as CascadeType.ALL . Here is how it looks for the Contact entity: @ManyToMany(cascade= CascadeType.ALL) private List<Contact> parentContacts = new ArrayList<Contact>(); @ManyToMany(cascade= CascadeType.ALL, mappedBy="parentContacts") private List<Contact> childContacts = new ArrayList<Contact>(); I have a method on the server side supposed to do save this entity: public AltContact saveContact

Prevent unwanted cascaded table updates

↘锁芯ラ 提交于 2019-12-13 18:41:55
问题 I am creating my first JPA based project. My application features several tables with foreign key relationships for integrity purposes. Many related tables are normalized lookup tables. Consider the tables Person and Account , having a fk relationship on accountid : +-Person----+ | personid | +-Account---+ | accountid*|==============>| accountid | | ... | | ... | +-----------+ +-----------+ In the front end (JSF), I created a form for new Person objects containing a selectOneMenu list with