Dapper总结（一）---基本CRUD操作

 一、dapper是什么

　　dapper是一款轻量级的ORM(Object Relationship Mapper)，它负责数据库和编程语言之间的映射。SqlConnection,MysqlConnection,OracleConnection都是继承于DBConnection，而DBConnection又是实现了IDBConnection的接口。因为Dapper是对IDBConnection接口进行了方法扩展，比如你看到的SqlMapper.cs，所以dapper支持多数据库。

二、dapper的简单使用

0、准备的测试类

 1   //用户类
 2     public class UserInfo
 3     {
 4         public int UId { get; set; }//用户Id
 5         public string UserName { get; set; }//用户名
 6         public int Age { get; set; }//年龄
 7         public int RoleId { get; set; }//角色Id
 8 
 9     }
10     //角色类
11     public class RoleInfo
12     {
13         public int RId { get; set; }//角色Id
14         public string RoleName { get; set; }//角色名
15     }

1、execute方法，返回值为int类型，表示受影响行数

 1  　　　　//插入数据
 2             //单条数据插入
 3             int result = conn.Execute("insert into userinfo values(@username,@age,@roleid)", new
 4             {
 5                 UserName = "user1",
 6                 Age = 20,
 7                 RoleId = 1
 8             });  // result=1
 9 
10             //多条数据插入
11             List users=new List(){
12                  new UserInfo(){UserName="user2",Age=22,RoleId=1},
13                  new UserInfo(){UserName="user3",Age=23,RoleId=1},
14                  new UserInfo(){UserName="user4",Age=24,RoleId=2},
15                                  };
16 
17             int result2 = conn.Execute("insert into userinfo values(@username,@age,@roleid)", users); // result2=3        
18 
19         //修改
20             int rusultEdit = conn.Execute("update userinfo set age=25 where username=@username", new { UserName = "user0" });
21 
22        //删除
23             int resultDel = conn.Execute("delete from userinfo where uid=@uid", new { UId = 6 });

2、Query方法，返回值为IEnumerable类型

 1   　 //带参数查询 例子：查询用户名为user1,年龄为20的用户
 2             IEnumerable query1 = conn.Query("select * from userinfo where age=@Age and username=@username", new{Age=20,UserName="user1"})
3       
 4      //in查询    例子：查询年龄是20,21，或22的用户
 5             IEnumerable query2=conn.Query("select * from userinfo where age in @ages",new {ages=new int [3]{20,21,22}});
 6            
 7      //返回多个结果集   例子：查询用户列表和角色列表       
 8             var sql = "select * from userinfo; select * from roleinfo";
 9             var query3 = conn.QueryMultiple(sql);//GridReader类型
10             var usesList = query3.Read();//IEnumberable类型
11             var roleList = query3.Read();
12 
13     //表连接查询  例子：查询用户信息和其对应的角色名
14         //1、返回强类型结果 
15             var sql2 = @"select u.username,u.age,u.uid ,r.rolename from userinfo as u join roleinfo as r on u.roleid=r.rid";
16             var result2 = conn.Query(sql2, (user, role) =>
17             {
18                 user.Role = role;
19                 return user;
20             }, splitOn: "RoleName");//splitOn参数表示分割，前边的是第一个对象的属性，后边的是第二个对象的属性
21 
22         //2、返回动态类型结果
23             var result3 = conn.Query(sql2);
24             foreach (var item in result3)
25             {
26                 Console.WriteLine("username:{0},rolename:{1}", item.username, item.rolename);
27             }

 

转载于:https://www.cnblogs.com/wyy1234/p/9077551.html