关于sql:union-分页groupjoin-复杂查询net-coreframework

union 分页 /group/join 简单查问 (.net core/framework)

unoin 是一个比拟非凡的查问，对 union 进行分页，关联，分组须要在最里面包装一层，如果对 union 后果再进行其它关联，分组，复杂度直线回升，解决此问题

1. 装置 nuget 包：CRL
2. using CRL;

以下为默认数据源实现

如果应用 ef core 和 ado.net 见:Data/EFTest · hubroxxl/CRL – 码云 – 开源中国 (gitee.com)

定义数据源

var builder = DBConfigRegister.GetInstance();
builder.RegisterDBAccessBuild(dbLocation =>
        {return new DBAccessBuild(DBType.MSSQL, "server=.;database=testDb; uid=sa;pwd=123;");
        });

定义对象管理器

public class ProductRepository:BaseProvider<ProductData>
{
    public static ProductRepository Instance
        {get { return  new ProductRepository(); }
        }
}

通过 GetLambdaQuery 办法创立 ILambdaQuery

ILambdaQuery 能实现子查问和嵌套查问，只有合乎 T -SQL 语义逻辑，能够应用 ILambdaQueryResultSelect 有限叠加

如：

• join 后 group
• join 后再 join
• group 后再 join
• join 一个 group 后果
• join 一个 union 后果
• 对 union 进行 group 再 join
• …

简略的 union

var query = ProductRepository.Instance.GetLambdaQuery().Where(b => b.Id < 200);
            var query2 = query.CreateQuery<Code.Order>().Where(b => b.Id < 200);
            var view1 = query.Select(b => new { a1 = b.Id, a2 = b.ProductName});
            var view2 = query2.Select(b => new { a1 = b.Id, a2 = b.Remark});
            var result = view1.Union(view2).OrderBy(b => b.a1).OrderBy(b => b.a2, false).ToList();
            var sql = query.PrintQuery();

生成 SQL 为

select t1.[Id] as a1,t1.[ProductName1] as a2 from [ProductData] t1  with (nolock)  where (t1.[Id]<'200')
 union all
select t2.[Id] as a1,t2.[Remark] as a2 from [OrderProduct] t2  with (nolock)  where (t2.[Id]<'200')
  order by [a1] desc,[a2] asc

对 union 进行分页

var query = ProductRepository.Instance.GetLambdaQuery().Where(b => b.Id < 200);
            query.Take(10);
            var query2 = query.CreateQuery<Code.Order>().Where(b => b.Id < 200).Take(5);
            var view1 = query.Select(b => new { a1 = b.Id, a2 = b.ProductName});
            var view2 = query2.Select(b => new { a1 = b.Id, a2 = b.Remark});
            var union = view1.Union(view2).OrderBy(b => b.a1).OrderBy(b => b.a2, false);
            union.UnionPage(15, 1);// 分页参数
            var result = union.ToList();
            var sql = query.PrintQuery();

生成 SQL 为

SELECT * FROM (select a1,a2,ROW_NUMBER() OVER (Order by [a1] desc,[a2] asc ) AS RowNumber  from (select top 10 t1.[Id] as a1,t1.[ProductName1] as a2 from [ProductData] t1  with (nolock)  where (t1.[Id]<200)
 union all 
select top 5 t2.[Id] as a1,t2.[Remark] as a2 from [OrderProduct] t2  with (nolock)  where (t2.[Id]<200)) tu) T WHERE T.RowNumber BETWEEN 1 AND 15 order by RowNumber

union 后再 join

var query = ProductRepository.Instance.GetLambdaQuery().Where(b => b.Id < 200);
            query.Take(10);
            var query2 = query.CreateQuery<Code.Order>().Where(b => b.Id < 200).Take(5);
            var view1 = query.Select(b => new { a1 = b.Id, a2 = b.ProductName});
            var view2 = query2.Select(b => new { a1 = b.Id, a2 = b.Remark});
            var union = view2.Union(view1).OrderBy(b => b.a1).OrderBy(b => b.a2, false);
            var join = query.Join(union, (a, b) => a.Id == b.a1).Select((a, b) => new {a.Id, b.a2});//join
            var result = join.ToList();
            var sql = query.PrintQuery();

生成 SQL 为

select top 10 t1.[Id],t3.[a2] as a2 from [ProductData] t1  with (nolock)  Inner join (select top 5 t2.[Id] as a1,t2.[Remark] as a2 from [OrderProduct] t2  with (nolock)  where (t2.[Id]<'200')
 union all 
select top 10 t1.[Id] as a1,t1.[ProductName1] as a2 from [ProductData] t1  with (nolock)  where (t1.[Id]<'200')
  order by [a1] desc,[a2] asc) t3  on t1.[Id]=t3.a1 where (t1.[Id]<'200')

union 后再 group

var query = ProductRepository.Instance.GetLambdaQuery().Where(b => b.Id < 200);
            var query2 = query.CreateQuery<Code.Order>().Where(b => b.Id < 200);
            var view1 = query.Select(b => new { a1 = b.Id, a2 = b.ProductName});
            var view2 = query2.Select(b => new { a1 = b.Id, a2 = b.Remark});
            var union = view1.Union(view2).OrderBy(b => b.a2, false);
            var group = union.UnionGroupBy(b => b.a2);//group
            var result = group.Select(b => new { b.a2}).ToList();
            var sql = query.PrintQuery();

生成 SQL 为

select a2 from (select t1.[Id] as a1,t1.[ProductName1] as a2 from [ProductData] t1  with (nolock)  where (t1.[Id]<'200')
 union all
select t2.[Id] as a1,t2.[Remark] as a2 from [OrderProduct] t2  with (nolock)  where (t2.[Id]<'200')) tu group by a2
  order by [a2] asc

源码示例参考

Data/QueryTest/test · hubroxxl/CRL – 码云 – 开源中国 (gitee.com)