我要评论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
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
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
objectquery<dbdatarecord> result = entities.createquery<dbdatarecord>("select value it from oracleentities.user as it ");
（3）按条件查
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：
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。
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