首页 > 代码库 > Entity Framework with MySQL 学习笔记一(insert,update,delete)
Entity Framework with MySQL 学习笔记一(insert,update,delete)
先说说 insert 吧.
当EF执行insert时，如果我们传入的对象是有关联(1对多等)的话，它会执行多个语句 insert到多个表，
并且再select出来填充我们的属性(因为有些column默认值是sql设定的，比如id等，我们insert后要有最新的数据丫).
using (EFDB db = new EFDB()){ db.prods.Add(new Prod { code = "mk100", name = "name", detail = new ProdDetail //1对1关系当 prod_detail table { fullDescription = "des" } }); db.SaveChanges();}
Opened connection at 2014/9/28 15:33:53 +08:00Started transaction at 2014/9/28 15:33:53 +08:00SET SESSION sql_mode=‘ANSI‘;INSERT INTO `prod`(`code`, `name`) VALUES (@gp1, @gp2);SELECT`id`FROM `prod` WHERE row_count() > 0 AND `id`=last_insert_id()-- @gp1: ‘mk100‘ (Type = String, IsNullable = false, Size = 5)-- @gp2: ‘name‘ (Type = String, IsNullable = false, Size = 4)-- Executing at 2014/9/28 15:33:53 +08:00-- Completed in 13 ms with result: EFMySqlDataReaderINSERT INTO `prod_detail`(`prod_id`, `id`, `fullDescription`) VALUES (7, 0, @gp1)-- @gp1: ‘des‘ (Type = String, IsNullable = false, Size = 3)-- Executing at 2014/9/28 15:33:53 +08:00-- Completed in 15 ms with result: 1Committed transaction at 2014/9/28 15:33:53 +08:00Closed connection at 2014/9/28 15:33:53 +08:00Disposed transaction at 2014/9/28 15:33:53 +08:00
delete 的话也有类似的情况，如果是关联的话，它也会执行多个语句去删除多个表，delete必须先把要洗掉的行select出来(这个似乎不太好...)
如果关联的数据是null,就不会去delete了，比如下面没有使用Include的话(虽然pk是有的，但是detail对象是Null)
WillCascadeOnDelete - Enabling Cascade Delete (级联删除) <-- 目前不清楚这样设置
using (EFDB db = new EFDB()){ //db.Configuration.LazyLoadingEnabled = false; db.prods.RemoveRange(db.prods.Where(p => p.id == 7).Include(p => p.detail)); //用include把关联select出来 db.SaveChanges();}
Opened connection at 2014/9/28 15:43:01 +08:00SELECT`Extent1`.`id`, `Extent1`.`code`, `Extent1`.`name`, `Extent2`.`prod_id`, `Extent2`.`id` AS `id1`, `Extent2`.`fullDescription`FROM `prod` AS `Extent1` LEFT OUTER JOIN `prod_detail` AS `Extent2` ON `Extent1`.`id` = `Extent2`.`prod_id` WHERE 7 = `Extent1`.`id`-- Executing at 2014/9/28 15:43:01 +08:00-- Completed in 14 ms with result: EFMySqlDataReaderClosed connection at 2014/9/28 15:43:01 +08:00Opened connection at 2014/9/28 15:43:02 +08:00Started transaction at 2014/9/28 15:43:02 +08:00DELETE FROM `prod_detail` WHERE `prod_id` = 7-- Executing at 2014/9/28 15:43:02 +08:00-- Completed in 13 ms with result: 1DELETE FROM `prod` WHERE `id` = 7-- Executing at 2014/9/28 15:43:02 +08:00-- Completed in 12 ms with result: 1Committed transaction at 2014/9/28 15:43:02 +08:00Closed connection at 2014/9/28 15:43:02 +08:00Disposed transaction at 2014/9/28 15:43:02 +08:00
update 也是先select出来，然后EF会再saveChange时对比之前的值然后生成语句update
using (EFDB db = new EFDB()){ //db.Configuration.LazyLoadingEnabled = false; var prod = db.prods.Where(p => p.id == 3).FirstOrDefault(); prod.name = "change"; db.SaveChanges();}
Opened connection at 2014/9/28 15:46:09 +08:00SELECT`Extent1`.`id`, `Extent1`.`code`, `Extent1`.`name`FROM `prod` AS `Extent1` WHERE 3 = `Extent1`.`id` LIMIT 1-- Executing at 2014/9/28 15:46:09 +08:00-- Completed in 11 ms with result: EFMySqlDataReaderClosed connection at 2014/9/28 15:46:09 +08:00Opened connection at 2014/9/28 15:46:09 +08:00Started transaction at 2014/9/28 15:46:09 +08:00UPDATE `prod` SET `name`=@gp1 WHERE `id` = 3-- @gp1: ‘change‘ (Type = String, IsNullable = false, Size = 6)-- Executing at 2014/9/28 15:46:09 +08:00-- Completed in 11 ms with result: 1Committed transaction at 2014/9/28 15:46:09 +08:00Closed connection at 2014/9/28 15:46:09 +08:00Disposed transaction at 2014/9/28 15:46:09 +08:00
EF 6 默认情况会使用 Transaction 的.
比如当我们对实体做了很多修改，最后调用saveChange().EF会开启Transaction然后执行多个语句，如果其中一个语句有问题，就会rollBack
需要注意的是，每一次saveChange都会开启和关闭一次 tansaction ，所以如果你调用多次的话，自己要搞清楚
using (EFDB db = new EFDB()){ //db.Configuration.LazyLoadingEnabled = false; var prod = db.prods.Where(p => p.id == 3).Include(p => p.detail).FirstOrDefault(); prod.name = "change22"; db.SaveChanges(); prod.detail.fullDescription = "zzz"; db.SaveChanges();}
Opened connection at 2014/9/28 16:14:19 +08:00Started transaction at 2014/9/28 16:14:19 +08:00UPDATE `prod` SET `name`=@gp1 WHERE `id` = 3-- @gp1: ‘change22‘ (Type = String, IsNullable = false, Size = 8)-- Executing at 2014/9/28 16:14:19 +08:00-- Completed in 13 ms with result: 1Committed transaction at 2014/9/28 16:14:19 +08:00Closed connection at 2014/9/28 16:14:19 +08:00Disposed transaction at 2014/9/28 16:14:19 +08:00Opened connection at 2014/9/28 16:14:19 +08:00Started transaction at 2014/9/28 16:14:19 +08:00UPDATE `prod_detail` SET `fullDescription`=@gp1 WHERE `prod_id` = 3-- @gp1: ‘zzz‘ (Type = String, IsNullable = false, Size = 3)-- Executing at 2014/9/28 16:14:19 +08:00-- Completed in 12 ms with result: 1Committed transaction at 2014/9/28 16:14:19 +08:00Closed connection at 2014/9/28 16:14:19 +08:00Disposed transaction at 2014/9/28 16:14:19 +08:00
还有一种方式是，让我们自己来控制
using (EFDB db = new EFDB()){ using (var trans = db.Database.BeginTransaction()) { try { //db.Configuration.LazyLoadingEnabled = false; var prod = db.prods.Where(p => p.id == 3).Include(p => p.detail).FirstOrDefault(); prod.name = "xx1234"; db.SaveChanges(); prod.detail.fullDescription = "123"; throw new Exception("x"); //即使这里有问题，上一个saveChange也能rollBack db.SaveChanges(); trans.Commit(); } catch (Exception) { trans.Rollback(); } }}
Opened connection at 2014/9/28 16:16:06 +08:00Started transaction at 2014/9/28 16:16:06 +08:00SELECT`Extent1`.`id`, `Extent1`.`code`, `Extent1`.`name`, `Extent2`.`prod_id`, `Extent2`.`id` AS `id1`, `Extent2`.`fullDescription`FROM `prod` AS `Extent1` LEFT OUTER JOIN `prod_detail` AS `Extent2` ON `Extent1`.`id` = `Extent2`.`prod_id` WHERE 3 = `Extent1`.`id` LIMIT 1-- Executing at 2014/9/28 16:16:06 +08:00-- Completed in 12 ms with result: EFMySqlDataReaderUPDATE `prod` SET `name`=@gp1 WHERE `id` = 3-- @gp1: ‘xx12234‘ (Type = String, IsNullable = false, Size = 7)-- Executing at 2014/9/28 16:16:07 +08:00-- Completed in 11 ms with result: 1Rolled back transaction at 2014/9/28 16:16:07 +08:00Disposed transaction at 2014/9/28 16:16:07 +08:00Closed connection at 2014/9/28 16:16:07 +08:00
Entity Framework with MySQL 学习笔记一(insert,update,delete)
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。