Choe.Orm框架下

Choe.Orm框架下的mysql技术

高效开发的NET.c#数据库访问框架（ORM）查询接口使用lambda表达式，使用对象的方法可以完成多表查询，分组查询，聚合查询，插入数据和批量操作。

public enum Gender

{

Man = 1,

Woman

}

[Table(“Users”)]

public class User

{

[Column(IsPrimaryKey = true)]

[AutoIncrement]

public int Id { get; set; }

public string Name { get; set; }

public Gender? Gender { get; set; }

public int? Age { get; set; }

public int? CityId { get; set; }

public DateTime? OpTime { get; set; }

}

public class City

{

[Column(IsPrimaryKey = true)]

public int Id { get; set; }

public string Name { get; set; }

public int ProvinceId { get; set; }

}

public class Province

{

[Column(IsPrimaryKey = true)]

public int Id { get; set; }

public string Name { get; set; }

}

建个 MySqlConnectionFactory 类，实现 IDbConnectionFactory 接口：

public class MySqlConnectionFactory : IDbConnectionFactory

{

string _connString = null;

public MySqlConnectionFactory(string connString)

{

this._connString = connString;

}

public IDbConnection CreateConnection()

{

MySqlConnection conn = new MySqlConnection(this._connString);

return conn;

}

}

创建一个 DbContext：

MySqlContext context = new MySqlContext(new MySqlConnectionFactory(DbHelper.ConnectionString));

再创建一个 IQuery：

IQuery q = context.Query();

查询数据

基本查询

IQuery q = context.Query();

q.Where(a => a.Id == 1).FirstOrDefault();

/*

SELECT

Users

.

Id

AS

Id

,

Users

.

Name

AS

Name

,

Users

.

Gender

AS

Gender

,

Users

.

Age

AS

Age

,

Users

.

CityId

AS

CityId

,

Users

.

OpTime

AS

OpTime

FROM

Users

AS

Users

WHERE

Users

.

Id

= 1 LIMIT 0,1

*/

//可以选取指定的字段

q.Where(a => a.Id == 1).Select(a => new { a.Id, a.Name }).FirstOrDefault();

/*

SELECT

Users

.

Id

AS

Id

,

Users

.

Name

AS

Name

FROM

Users

AS

Users

WHERE

Users

.

Id

= 1 LIMIT 0,1

*/

//分页

q.Where(a => a.Id > 0).OrderBy(a => a.Age).Skip(1).Take(999).ToList();

/*

SELECT

Users

.

Id

AS

Id

,

Users

.

Name

AS

Name

,

Users

.

Gender

AS

Gender

,

Users

.

Age

AS

Age

,

Users

.

CityId

AS

CityId

,

Users

.

OpTime

AS

OpTime

FROM

Users

AS

Users

WHERE

Users

.

Id

> 0 ORDER BY

Users

.

Age

ASC LIMIT 1,999

*/

连接查询

IQuery users = context.Query();

IQuery cities = context.Query();

IQuery provinces = context.Query();

//建立连接

IJoiningQuery