递归查询以加快系统的速度

Question

我的应用程序使用父子关系读取一个表。应用程序自己查询树的每个级别，并且它确实很慢（必须深入多级）。我正在寻找另一个解决方案并来到递归查询。用我发现的例子，我不能将它映射到我的数据结构。

我的结构是这样的：

CREATE TABLE [products].[BillOfMaterial](
    [id] [bigint] IDENTITY(1,1) NOT NULL, 
    [parentNumber] [nvarchar](50) NOT NULL, 
    [warehouse] [nvarchar](50) NOT NULL, 
    [sequenceNumber] [int] NOT NULL, 
    [childNumber] [nvarchar](50) NOT NULL, 
    [childDescription] [nvarchar](50) NULL, 
    [qtyRequired] [numeric](18, 3) NOT NULL, 
    [childItemClass] [nvarchar](50) NULL, 
    [childItemType] [nvarchar](50) NULL, 
    [scrapFactor] [numeric](18, 3) NULL, 
    [bubbleNumber] [int] NOT NULL, 
    [operationNumber] [int] NOT NULL, 
    [effectivityDate] [date] NULL, 
    [discontinuityDate] [date] NULL, 
    [companyID] [bigint] NOT NULL, 
CONSTRAINT [PK_BillOfMaterial] PRIMARY KEY CLUSTERED 
(
    [id] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] 

一些示例数据：

当我查询parentNumber 1就应该给我所有的那些行：

而对于parentNumber 3输出必须是：

现在我需要一个父母的所有孩子递归的方式。我怎样才能实现这只使用SQL？ （我正在使用SQL服务器）

我试过已经在sql中使用with语句，但它现在会给出很多结果。

WITH bom ([id] 
     ,[parentNumber] 
     ,[warehouse] 
     ,[sequenceNumber] 
     ,[childNumber] 
     ,[childDescription] 
     ,[qtyRequired] 
     ,[childItemClass] 
     ,[childItemType] 
     ,[scrapFactor] 
     ,[bubbleNumber] 
     ,[operationNumber] 
     ,[effectivityDate] 
     ,[discontinuityDate] 
     ,[companyID]) 
AS 
(
    select * from [CR_ApplicationSuite].[products].[BillOfMaterial] where parentNumber IN ('F611882261', '2912435206') 
UNION ALL 
select b.* from [CR_ApplicationSuite].[products].[BillOfMaterial] b 
INNER JOIN [CR_ApplicationSuite].[products].[BillOfMaterial] c on c.childNumber = b.parentNumber 
) 
SELECT * 
FROM bom 

Answer 1

下面是一个使用表变量进行演示的示例。

对于递归查询，您需要在其内部使用CTE。

我包含了一个rootParentNumber，所以它的基础父母是什么更明显。

WHERE子句在示例中进行了注释。 因为您可以在递归查询中或在外部查询中放置WHERE子句。前者应该更快。

declare @BillOfMaterial TABLE (
    [id] [bigint] IDENTITY(1,1) NOT NULL, 
    [parentNumber] [nvarchar](50) NOT NULL, 
    [warehouse] [nvarchar](50) NOT NULL, 
    [sequenceNumber] [int] NOT NULL, 
    [childNumber] [nvarchar](50) NOT NULL, 
    [childDescription] [nvarchar](50) NULL, 
    [qtyRequired] [numeric](18, 3) NOT NULL, 
    [childItemClass] [nvarchar](50) NULL, 
    [childItemType] [nvarchar](50) NULL, 
    [scrapFactor] [numeric](18, 3) NULL, 
    [bubbleNumber] [int] NOT NULL, 
    [operationNumber] [int] NOT NULL, 
    [effectivityDate] [date] NULL, 
    [discontinuityDate] [date] NULL, 
    [companyID] [bigint] NOT NULL 
); 

insert into @BillOfMaterial (parentNumber, childNumber, warehouse, sequenceNumber, qtyRequired, bubbleNumber, operationNumber, companyID) values 
('1','2','WH1',1,0,0,0,1), 
('2','4','WH1',2,0,0,0,1), 
('3','4','WH1',3,0,0,0,1), 
('4','5','WH1',4,0,0,0,1), 
('5','0','WH1',5,0,0,0,1); 

WITH BOM 
AS 
(
    select parentNumber as rootParentNumber, * 
    from @BillOfMaterial 
    --where parentNumber IN ('1','3') 

    union all 

    select bom.rootParentNumber, b.* 
    from BOM 
    INNER JOIN @BillOfMaterial b 
    on (BOM.childNumber = b.parentNumber and b.childNumber <> '0') 
) 
SELECT 
[rootParentNumber] 
,[parentNumber] 
,[childNumber] 
,[id] 
,[warehouse] 
,[sequenceNumber] 
,[childDescription] 
,[qtyRequired] 
,[childItemClass] 
,[childItemType] 
,[scrapFactor] 
,[bubbleNumber] 
,[operationNumber] 
,[effectivityDate] 
,[discontinuityDate] 
,[companyID] 
FROM BOM 
--WHERE rootParentNumber IN ('1','3') 
ORDER BY [rootParentNumber], [parentNumber], [childNumber] 
;