为每个给定的父ID自动增加子订单项

如何解决为每个给定的父ID自动增加子订单项

我不知道该主题的正确行话，所以去了。我有一个像这样构建的sql表：

CREATE TABLE [dbo].[MANUAL_LINE_ITEMS]
  ( [SHIPMENT_ID] [int] NOT NULL,[LINE_ITEM_ID] [int] NOT NULL,[JOB_NUMBER] [nvarchar](50) NULL,[RELEASE_NUMBER] [nvarchar](50) NULL,[NO_OF_PCS] [nvarchar](50) NULL,[DESCRIPTION] [nvarchar](100) NULL,[SSMA_TimeStamp] [timestamp] NOT NULL,CONSTRAINT PK_MANUAL_LINE_ITEMS_SHIPMENT_ID_LINE_ITEM_ID PRIMARY KEY CLUSTERED ([SHIPMENT_ID],[LINE_ITEM_ID])
   WITH (PAD_INDEX = OFF,STATISTICS_norECOmpuTE = OFF,IGnorE_DUP_KEY = OFF,ALLOW_ROW_LOCKS = ON,ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]

我希望LINE_ITEM_ID为每个SHIPMENT_ID自动递增，然后为下一个重置。我的SHIPMENTS表格如下：

CREATE TABLE [dbo].[SHIPMENTS]
  ( [SHIPMENT_ID] [int] identity(1,1) NOT NULL,[JOB] [nvarchar](50) NOT NULL,[REL] [nvarchar](50) NOT NULL,[SHIPMENT_NUMBER] [int] NOT NULL,[DATE] [datetime2](0) NULL,[FREIGHTCHARGE] [smallmoney] NULL,[SHIPPER] [nvarchar](50) NULL,[MANUAL_LINE_ITEM_ENTRY] [bit] NULL,...,CONSTRAINT PK_SHIPMENTS_SHIPMENT_ID_JOB_REL_SHIPMENT_NUMBER PRIMARY KEY CLUSTERED ([SHIPMENT_ID],[JOB],[REL],[SHIPMENT_NUMBER])
   WITH (PAD_INDEX = OFF,ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]

“装运”的“访问”表单使用子表单来添加/列出订单项详细信息。如果需要，我可以重新处理sql表或使用Access VBA事件。为了使每个SHIPMENT_ID的LINE_ITEM_ID自动递增，需要做些什么？ TIA。