sql - SQL 中垂直联合列

Question

假设这些表:

组:(Id，标题):{1,G1}, {2,G2}, {3,G3}, {4, G4}

类别:(Id，标题):{1, Cat1}, {2, Cat2}, {3, Cat3}, {4, Cat4}

产品:(Id、GroupId、CategoryId、名称):

{1, 1, 1, G1C1P1},
{2, 1, 2, G1C2P2},
{3, 1, 2, G1C2P3},
{4, 2, 2, G2C2P4},
{5, 2, 2, G2C2P5},
{6, 3, 1, G3C1P6},
{7, 3, 3, G3C3P7}

经销商: (Id, Name): {1, 'Dealer1'}, {2, 'Dealer2'}, {3, 'Dealer3'}

ProductDealer(Id、ProductId(英国)、DealerId、LastSale、Number):

{1, 1, 1, 5, '2012-12-10 12:34:31'}, 
{2, 2, 2, 120, '2012-11-10 12:34:31'}, 
{3, 5, 1, 75, '2012-12-02 12:34:31'}

所以我要创建产品的完整 View ，这是我的第一次尝试:

SELECT 
    [PR].[Id],
    [PR].[Name],
    [PR].[GroupId],
    [GR].[Title] AS [Group],
    [PR].[CategoryId],
    [CA].[Title] AS [Category]

FROM [dbo].[Product] AS [PR]
INNER JOIN [dbo].[Group] AS [GR] ON [PR].[GroupId] = [GR].[Id]
INNER JOIN [dbo].[Category] AS [CA] ON [PR].[CategoryId] = [CA].[Id]

然后我想添加ProductDealer列来查看，所以我试试这个:

SELECT 
    [PR].[Id],
    [PR].[Name],
    [PR].[GroupId],
    [GR].[Title] AS [Group],
    [PR].[CategoryId],
    [CA].[Title] AS [Category],
    ISNULL(
    (SELECT [PD].[Id] FROM [dbo].[ProductDealer] AS [PD] 
     WHERE [PD].[ProductId] = [PR].[Id]),
     CAST(-1 AS BIGINT)
    ) AS [ProductDealerId],
    ISNULL(
    (SELECT [DE].[Id] FROM [dbo].[Dealer] AS [DE]
    INNER JOIN [dbo].[ProductDealer] AS [PD] ON [DE].[Id] = [PD].[DealerId]
     WHERE [PD].[ProductId] = [PR].[Id]),
     CAST(-1 AS BIGINT)
    ) AS [DealerId],
     ISNULL(
    (SELECT [DE].[Name] FROM [dbo].[Dealer] AS [DE]
    INNER JOIN [dbo].[ProductDealer] AS [PD] ON [DE].[Id] = [PD].[DealerId]
     WHERE [PD].[ProductId] = [PR].[Id]),
     CAST('HaveNotDealer' AS NVARCHAR)
    ) AS [Dealer],
    ISNULL(
    (SELECT [PD].[LastSale] FROM [dbo].[ProductDealer] AS [PD] 
     WHERE [PD].[ProductId] = [PR].[Id]),
    CAST('0001-01-01 00:00:01' AS DATETIME2)
    ) AS [LastSale],
    ISNULL(
    (SELECT [PD].[Number] FROM [dbo].[ProductDealer] AS [PD] 
     WHERE [PD].[ProductId] = [PR].[Id]),
    CAST(0 AS BIGINT)
    ) AS [SaleNumber]

FROM [dbo].[Product] AS [PR]
INNER JOIN [dbo].[Group] AS [GR] ON [PR].[GroupId] = [GR].[Id]
INNER JOIN [dbo].[Category] AS [CA] ON [PR].[CategoryId] = [CA].[Id]

如您所见，对于 ProductDealer 中的每一列，我编写了一个完整的选择查询，我不知道是否有更好的方法来执行此操作？将这些列合并到第一个 View 之类的东西，你对最好地实现它有什么建议？

更新

在 ProductDealer 表中，ProductId 是英国的，所以每个产品可能有一个经销商或没有，如果产品有经销商，我想得到 ProductDealer 列在 View 中，如果没有，则获取我的默认值，如:(-1, 'HaveNotDealer')。

Answer 1

SELECT 
    [PR].[Id],
    [PR].[Name],
    [PR].[GroupId],
    [GR].[Title] AS [Group],
    [PR].[CategoryId],
    [CA].[Title] AS [Category],
    ISNULL([PD].[Id],
    CAST(-1 AS BIGINT)) AS [ProductDealerId],
    ISNULL([D].Id,
    CAST(-1 AS BIGINT)) as DealerId,
    ISNULL([D].Name,
    CAST('HaveNotDealer' AS NVARCHAR)) as DealerName,
    ISNULL(PD.LastSale,
    CAST('0001-01-01 00:00:01' AS DATETIME2)) as LastSale,
    ISNULL([PD].Number,
    CAST(0 AS BIGINT)) as SaleNumber

FROM [dbo].[Product] AS [PR]
INNER JOIN [dbo].[Group] AS [GR] ON [PR].[GroupId] = [GR].[Id]
INNER JOIN [dbo].[Category] AS [CA] ON [PR].[CategoryId] = [CA].[Id]
LEFT OUTER JOIN [dbo].[ProductDealer] AS [PD] ON [PR].[Id] = [PD].[ProductId]
LEFT OUTER JOIN [dbo].[Dealer] AS [D] ON [PD].DealerId = [D].Id