OleDbConnection，OracleConnection 或者SqlConnection这种连接，直接执行sql语句。现在的连接方式执行sql语句有了很大的不同，下面先看看简单的单表的增删改查操作，然后再看多表的关联查询，带参数查询等。

	一、ADO.NET Entity对单表的增删改查

	有一个表，即在工程中是一个实体user，为了测试方便，所有字段为string型。

	

	1、增加新记录

	增加一条记录如下：

	[csharp] 

	using (OracleEntities entities = new OracleEntities()) 

	{ 

	               User uer = User.CreateUser("id", "name", "age", "1"); 

	

	               entities.User.AddObject(user); 

	

	               entities.SaveChanges(); 

	 using (OracleEntities entities = new OracleEntities())

	 {

	                User uer = User.CreateUser("id", "name", "age", "1");

	                entities.User.AddObject(user);

	                entities.SaveChanges();

	}

	2、删除内容

	复制代码 代码如下:

	 

	using (OracleEntities entities = new OracleEntities()) 

	 { 

	                User user = entities.User.First<User>(a => a.ID.Equals("id")); 

	

	                entities.DeleteObject(user); 

	

	                entities.SaveChanges(); 

	} 
	

		 
	

		using (OracleEntities entities = new OracleEntities())

		 {

		                User user = entities.User.First<User>(a => a.ID.Equals("id"));
	

		                entities.DeleteObject(user);
	

		                entities.SaveChanges();

		}



3、修改内容


	复制代码 代码如下:

	 

	using (OracleEntities entities = new OracleEntities()) 

	 { 

	                User user = entities.User.First<User>(a => a.User.Equals("id")); 

	

	                user.Remarks = "修改了内容"; 

	

	                entities.SaveChanges(); 

	} 
	

		 
	

		using (OracleEntities entities = new OracleEntities())

		 {

		                User user = entities.User.First<User>(a => a.User.Equals("id"));
	

		                user.Remarks = "修改了内容";
	

		                entities.SaveChanges();

		}



4、查询内容

（1）实体直接查询

[/code] 

using (OracleEntities entities = new OracleEntities()) 

 { 

                ObjectQuery<User> result = entities.User;//查询所有  



                foreach (User item in result) 

                { 



                } 

} 

	 

	using (OracleEntities entities = new OracleEntities())

	 {

	                ObjectQuery<User> result = entities.User;//查询所有

	                foreach (User item in result)

	                {

	                }

	}

	[/code]

	（2）Esql查询

	复制代码 代码如下:

	

	ObjectQuery<DbDataRecord> result = entities.CreateQuery<DbDataRecord>("select value it  from  OracleEntities.User as it ");


（3）按条件查


	复制代码 代码如下:

	

	var result = entities.User.Where(o => o.id.Equals("id"));


二、关联查询

比如还有个表Other与User外键关联。


	 

	

	进行查询如下：

	复制代码 代码如下:

	 

	using (OracleEntities entities = new OracleEntities()) 

	 { 

	                string esql = "SELECT b.detail FROM OracleEntities.User as a,OracleEntities.Other as b where a.otherid = b.id and a.id='id'"; 

	

	                ObjectQuery<DbDataRecord> query = entities.CreateQuery<DbDataRecord>(esql); 

	

	                foreach (DbDataRecord r in query) 

	                { 

	                    string ss = r["detail"].ToString(); 

	                } 

	 } 
	

		 
	

		using (OracleEntities entities = new OracleEntities())

		 {

		                string esql = "SELECT b.detail FROM OracleEntities.User as a,OracleEntities.Other as b where a.otherid = b.id and a.id='id'";  www.jb51.net
	

		                ObjectQuery<DbDataRecord> query = entities.CreateQuery<DbDataRecord>(esql);
	

		                foreach (DbDataRecord r in query)

		                {

		                    string ss = r["detail"].ToString();

		                }

		 }



当然这些都是最基本的用法，因为使用的Linq和ESql，在后面再Linq和ESql的用法里再详细说明。