1、导航查询特点
作用：主要处理主对象里面有子对象这种层级关系查询
1.1 无外键开箱就用
其它ORM导航查询 需要 各种配置或者外键，而SqlSugar则开箱就用，无外键，只需配置特性和主键就能使用
1.2 高性能优
查询 性能非常强悍
支持大数据分页导航查询
3.3 语法超级爽
注意：多级查询时VS有时候没提示直接写就行了 ，相比 其他 .NET ORM语法要简单的多
var list=db.Queryable<Test>()
.Includes(x => x.Provinces,x=>x.Citys ,x=>x.Street)//多级查询 有时候VS没提示手写
.Includes(x => x.ClassInfo)// 一级查询
.ToList();
//多级查询 加排序过滤
.Includes(x =>x.Provinces.Where(z=>z.Id>0).OrderBy(z=>z.Id).ToList(),x=>x.Citys,x=>x.Street)
// 一级查询
.Includes(x =>x.ClassInfo)
.ToList();2、新导航查询 ORM
适合有主键的常规操作, 请升级到5.0.6.8
2.1 一对一
//实体
public class StudentA
{
[SugarColumn(IsPrimaryKey = true, IsIdentity = true)]
public int StudentId { get; set; }
public string Name { get; set; }
public int SchoolId { get; set; }
[Navigate(NavigateType.OneToOne, nameof(SchoolId))]//一对一
public SchoolA SchoolA { get; set; }
}
public class SchoolA
{
[SugarColumn(IsPrimaryKey = true, IsIdentity = true)]
public int SchoolId { get; set; }
public string SchoolName { get; set; }
}
//代码
var list2 = db.Queryable<StudentA>()
.Includes(x => x.SchoolA)
.Where(x => x.SchoolA.SchoolName == "北大")//可以对一级导航进行过滤
.ToList();2.2 一对多
//实体
public class StudentA
{
[SugarColumn(IsPrimaryKey = true, IsIdentity = true)]
public int StudentId { get; set; }
public string Name { get; set; }
public int SchoolId { get; set; }
[Navigate(NavigateType.OneToOne, nameof(SchoolId))]//一对一
public SchoolA SchoolA { get; set; }
}
public class SchoolA
public string SchoolName { get; set; }
//代码
var list2 = db.Queryable<StudentA>()
.Includes(x => x.SchoolA)
.Where(x => x.SchoolA.SchoolName == "北大")//可以对一级导航进行过滤
.ToList();2.3 多对多
//多对多
public class ABMapping1
{
[SugarColumn(IsPrimaryKey = true )]
public int AId { get; set; }
[SugarColumn(IsPrimaryKey = true)]
public int BId { get; set; }
}
public class A1
{
[SugarColumn(IsPrimaryKey = true, IsIdentity = true )]
public int Id { get; set; }
public string Name { get; set; }
[Navigate(typeof(ABMapping1),nameof(ABMapping1.AId),nameof(ABMapping1.BId))]
public List<B1> BList { get; set; }
}
public class B1
{
[SugarColumn(IsPrimaryKey = true , IsIdentity = true)]
public int Id { get; set; }
public string Name { get; set; }
[Navigate(typeof(ABMapping1), nameof(ABMapping1.BId), nameof(ABMapping1.AId))]
public List<A1> AList { get; set; }
}
//例1:简单用法
var list3= db.Queryable<A1>().Includes(x => x.BList).ToList();
//例2:支持子对象排序和过滤
var list3= db.Queryable<A1>().Includes(x => x.BList.Where(z=>z.Id>0).ToList()).ToList();
//例3:支持主表过滤 Any和Count
var list3= db.Queryable<A1>().Includes(x => x.BList)
.Where(x=>x.BList .Any(z=>z.Id ==1)).ToList();2.4 多级查询
配置好实体类，我们可以多级查询 ，.NET 中轻松多级查询
var list=db.Queryable<Test>()
.Includes(x => x.Provinces,x=>x.Citys ,x=>x.Street)//有时候没提示 直接写
.Includes(x => x.ClassInfo)// 一级查询
.ToList();2.5 大数据分页导航
适合一次性查询1000条以上的导航
var list = new List<Tree1>();
db.Queryable<Tree1>()
.Includes(it => it.Child)
.ForEach(it => list.Add(it), 300); //每次查询300条 更多用法：https://www.donet5.com/Home/Doc?typeId=2414
3、ORM无配置映射（高性能）
适合没有主键或者复杂的一些操作
3.1 无配置映射实现二层
结构: Student->SchoolA
var list = db.Queryable<StudentA>().ToList();
db.ThenMapper(list, stu =>
{
//如果加Where不能带有stu参数，stu参数写到 SetContext
stu.SchoolA=db.Queryable<SchoolA>().SetContext(scl=>scl.SchoolId,()=>stu.SchoolId,stu).FirstOrDefault();
});
// SetContext不会生成循环操作，高性能 和直接Where性能是不一样的如果没有SetContext那么这个查询将会循环
3.2 无配置映射无限级
了解原理后我们用ThenMapper想映射哪层就映射哪层
var treeRoot=db.Queryable<Tree>().Where(it => it.Id == 1).ToList();
//第一层
db.ThenMapper(treeRoot, item =>
{
item.Child = db.Queryable<Tree>().SetContext(x => x.ParentId, () => item.Id, item).ToList();
});
//第二层
db.ThenMapper(treeRoot.SelectMany(it=>it.Child), it =>
{
it.Child = db.Queryable<Tree>().SetContext(x => x.ParentId, () => it.Id, it).ToList();
});
//第三层
db.ThenMapper(treeRoot.SelectMany(it => it.Child).SelectMany(it=>it.Child), it =>
{
it.Child = db.Queryable<Tree>().SetContext(x => x.ParentId, () => it.Id, it).ToList();
});
//这儿只是用树型结构来证明可以实现无限级别导航查询 ,实际开发中树型结构用ToTree实现
public class Tree
{
[SqlSugar.SugarColumn(IsPrimaryKey =true)]
public int Id { get; set; }
public string Name { get; set; }
public int ParentId { get; set; }
[SqlSugar.SugarColumn(IsIgnore = true)]
public Tree Parent { get; set; }
[SqlSugar.SugarColumn(IsIgnore = true)]
public List<Tree> Child { get; set; }
}
// SetContext不会生成循环操作，高性能 和直接Where性能是不一样的4 、.NET ORM 未来计划
Json to sql 正在开发中 ，未来将打造一套直接由前端操作数据库的API
{
"Queryable":"order",
Select:[ [{SqlFunc_AggregateMin:["id"]},"id"], [{SqlFunc_GetDate:[]},"Date"] ]
}将支持 权限过滤 ，验证，多表查询，层级导航查询 等
GitHUB 源码：
https://github.com/donet5/SqlSugar
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