union 分页/group/join 复杂查询(.net core/framework)

union 分页/group/join 复杂查询(.net core/framework)

unoin是一个比较特殊的查询，对union进行分页，关联，分组需要在最外面包装一层，如果对union结果再进行其它关联，分组，复杂度直线上升，解决此问题

1. 安装nuget包：CRL
2. using CRL;

以下为默认数据源实现

如果使用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方法创建ILambdaQuery

ILambdaQuery能实现子查询和嵌套查询，只要符合T-SQL语义逻辑，可以使用ILambdaQueryResultSelect无限叠加

如：

• join后group
• join后再join
• group后再join
• join一个group结果
• join一个union结果
• 对union进行group再join
• ...

简单的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)