.NET6跨服务器联表查询操作MySql、Oracle、SqlServer等相互联表(2)-木庄网络博客

Include 语法吗？改不了，我只能封装他的语法，或者添加扩展方法。

三、跨服务器跨库联表查询

SqlSugar来实现跨服务器联表查询

3.1 跨库查询之一对一

[Tenant("db2")]//在类的特性设置当前类属于哪个库
  public class OrderItem
 {
            [SqlSugar.SugarColumn(IsPrimaryKey = true, IsIdentity = true)]
            public int ItemId { get; set; }
            public int OrderId { get; set; }
            public decimal? Price { get; set; }
            [SqlSugar.SugarColumn(IsNullable = true)]
            public DateTime? CreateTime { get; set; }
            [Navigate(NavigateType.OneToOne,nameof(OrderId))] //设置关系 对应Order表主键
            public Order Order { get; set; }
 }
//通过ConfigId进行区分是哪个库
var db = new SqlSugarClient(new List<ConnectionConfig>()
{
  new ConnectionConfig(){ConfigId="db1",DbType=DbType.Sqlite,ConnectionString="DataSource=/Db_OrderDb.sqlite",IsAutoCloseConnection=true},
  new ConnectionConfig(){ConfigId="db2",DbType=DbType.Sqlite,ConnectionString="DataSource=/Db_OrderItemDb.sqlite",IsAutoCloseConnection=true }
});
 
//通过实体类特性[Tenant("db2")]自动映射不同数据库进行查询
var list=db.QueryableWithAttr<OrderItem>()
.Includes(z => z.Order)
.ToList(); //1行代码就搞定了2个库联表查询

3.2 跨库查询之一对多

[Tenant("db1")]//指定是db1  (OrderItem类设置为 db2)
 public class Order
 {
           [SugarColumn(IsPrimaryKey = true, IsIdentity = true)]
           public int Id { get; set; }
           public string Name { get; set; }
           public decimal Price { get; set; }
           [SugarColumn(IsNullable = true)]
           public DateTime CreateTime { get; set; }
           [SugarColumn(IsNullable = true)]
           public int CustomId { get; set; }
           [Navigate(NavigateType.OneToMany, nameof(OrderItem.OrderId))]//
           public List<OrderItem> Items { get; set; }
 }<br>
 var list = db.QueryableWithAttr<Order>()
                   .Includes(z => z.Items)//跨库一对多
                   .ToList();

3.3 跨库查询之多对多　　

我们将3个表扔进3个不同的库里面

var db = new SqlSugarClient(new List<ConnectionConfig>()
   {
       new ConnectionConfig(){ConfigId="A",DbType=DbType.Sqlite,ConnectionString="DataSource=/A_DB.sqlite",IsAutoCloseConnection=true},
       new ConnectionConfig(){ConfigId="B",DbType=DbType.Sqlite,ConnectionString="DataSource=/B_DB.sqlite",IsAutoCloseConnection=true  },
       new ConnectionConfig(){ConfigId="AB",DbType=DbType.Sqlite,ConnectionString="DataSource=/AB_DB.sqlite",IsAutoCloseConnection=true  }
 });

　实体

 [Tenant("A")]//指定为A库
        public partial class OperatorInfo
        {
            /// <summary>
            /// 主键
            /// </summary>
            [SugarColumn(IsPrimaryKey = true)]
            public int id { get; set; }
 
            /// <summary>
            /// 姓名
            /// </summary>
            public string realname { get; set; }
 
            /// <summary>
            /// 多角色
            /// </summary>
            [Navigate(typeof(OptRole), nameof(OptRole.operId), nameof(OptRole.roleId))]//配置导航
            public List<Role> Roles { get; set; }
        }
 
 
        [Tenant("B")]//指定为B库
        public partial class Role
        {
            /// <summary>
            /// 角色
            /// </summary>
            [SugarColumn(IsPrimaryKey = true )]
            public int id { get; set; }
 
            /// <summary>
            /// 角色名称
            /// </summary>
            public string name { get; set; }
  
        }
        [Tenant("AB")]//指定为AB库
        public partial class OptRole
        {
            /// <summary>
            ///
            /// </summary>
            [SugarColumn(IsPrimaryKey = true)]
            public int id { get; set; }
 
            /// <summary>
            ///
            /// </summary>
            public int operId { get; set; }
 
            /// <summary>
            ///
            /// </summary>
            public int roleId { get; set; }
 
 
        }
 
//3个库3个表进行多对多查询
var x=db.QueryableWithAttr<OperatorInfo>()
.Includes(z => z.Roles).ToList();

3.4 多个表查询我们可以这么写

//多个表联表
var x=db.QueryableWithAttr<TB>()
.Includes(z => z.A1)
.Includes(z => z.A2)
.Includes(z => z.A3).ToList();
 
//多个表嵌套联表
var x=db.QueryableWithAttr<TB>()
.Includes(z =>z.A1, z.Province,z=>z.City)//4个层级
.Includes(z => z.A2)
.Includes(z => z.A3).ToList();

3.5 手动指定多库

上面都是通多特性实现的多库查询，我们也可以手动指定数据库进行多库查询

var list =db.GetConnection("db1").Queryable<OrderItem>()//Orderitem是db1
               .CrossQuery(typeof(Order), "db2")//Order是db2
               .Includes(z => z.Order)
               .ToList();