LINQ series: LINQ to SQL concat/union

1. Concat

　　Single row concat

 var  expr = (from  P in   context.            Products  select   P.productname) . Concat ( from  C in   context.            Categories  select   C.categoryname ); foreach  (var  item in   expr) {Console.WriteLine (item);}  

var expr = context. Products    = p.productname)    . Concat (    context. Categories    = c.categoryname)    );

SELECT     [UnionAll1].[ProductName]  as [C1]     from(SELECT         [Extent1].[ProductName]  as [ProductName]         from [dbo].[Product]  as [Extent1]    UNION  All        SELECT         [Extent2].[CategoryName]  as [CategoryName]         from [dbo].[Category]  as [Extent2]) as [UnionAll1]

Multi-column Concat

var expr = context. Products    new     {        p.productid,         p.productname     })    . Concat (    context. Categories    new     {         = C.categoryid,         = c.categoryname     })    );

SELECT     [UnionAll1].[ProductID]  as [C1],     [UnionAll1].[ProductID1]  as [C2],     [UnionAll1].[ProductName]  as [C3]     from(SELECT         [Extent1].[ProductID]  as [ProductID],         [Extent1].[ProductID]  as [ProductID1],         [Extent1].[ProductName]  as [ProductName]         from [dbo].[Product]  as [Extent1]    UNION  All        SELECT         [Extent2].[CategoryID]  as [CategoryID],         [Extent2].[CategoryID]  as [CategoryID1],         [Extent2].[CategoryName]  as [CategoryName]         from [dbo].[Category]  as [Extent2]) as [UnionAll1]

2. Union

var expr = context. Products    = p.productname)    . Union (    context. Categories    = c.categoryname)    );

SELECT     [Distinct1].[C1]  as [C1]     from(SELECT DISTINCT         [UnionAll1].[ProductName]  as [C1]         from(SELECT             [Extent1].[ProductName]  as [ProductName]             from [dbo].[Product]  as [Extent1]        UNION  All            SELECT             [Extent2].[CategoryName]  as [CategoryName]             from [dbo].[Category]  as [Extent2]) as [UnionAll1]    )   as [Distinct1]

LINQ series: LINQ to SQL concat/union