SQL - 使用 Scope_Identity() 插入 - 获取记录 ID [英] SQL - INSERT with Scope_Identity() - getting the record id

问题描述

我有一个用 VB.NET 编写的 ASP.NET 页面，它通过使用带有 INNER JOINSELECT 语句将项目放入 GridView> 并且还允许您向发票添加项目.

I have an ASP.NET page written in VB.NET that gets the items into a GridView by using a SELECT statement with INNER JOIN and also allows you to add an item to the invoice.

INNER JOIN 从 items 和 project_items 获取数据.

INNER JOIN that gets data from items and project_items.

SELECT Items.item_id, Items.item_name, Items.item_cost, project_items.item_quantity
FROM Items 
INNER JOIN project_items
ON items.item_id = project_items.item_id 
WHERE project_items.project_id = @parameter

@parameter is Session("ProjectID")

(有一个外键project_items.item_id -> items.item_id.)

我尝试在 VB.NET 中使用 SQL 语句尝试同时插入两个表.我尝试的是尝试使用该数据获取创建的最后一条记录的 item_id 并插入到另一个表 (project_items) 中.但是，数据仅被输入到第一个表中.

I have an trying to use an SQL statement in VB.NET to try and INSERT into two tables simultaneously. What I tried is I tried to get the item_id of the last record created and insert into another table (project_items) by using that data. However, data is only being entered into the first table.

知道我能做什么吗?

这是代码:

Protected Sub btnAddItem_Click(sender As Object, e As EventArgs) Handles btnAddItem.Click

        Dim conn As New SqlConnection("Data Source=BRIAN-PCSQLEXPRESS;Initial Catalog=master_db;Integrated Security=True")
        Dim addItemComm As String = "SELECT item_id FROM project_items WHERE project_id=@ProjectID"
        Dim user_id_select As New Integer

        Dim addItemSQL As New SqlCommand

        conn.Open()

        addItemSQL = New SqlCommand(addItemComm, conn)
        addItemSQL.Parameters.AddWithValue("@ProjectID", Convert.ToInt32(Session("ProjectID")))


        Dim datareader As SqlDataReader = addItemSQL.ExecuteReader()


        datareader.Close()
        conn.Close()

        Dim AddNewItemComm As String = "INSERT INTO Items (item_name,  item_cost, item_code) VALUES (@ItemName, @ItemCost, @ItemCode); SELECT SCOPE_IDENTITY()"
        Dim AddNewItem2Comm As String = "INSERT INTO project_items (item_id, project_id, item_quantity) VALUES (@ItemID, @ProjectID, @ItemQuantity) "
        Dim AddNewItemSQL As New SqlCommand


        conn.Open()

        AddNewItemSQL = New SqlCommand(AddNewItemComm, conn)
        AddNewItemSQL.Parameters.AddWithValue("@ItemName", txtItemName.Text.Trim)
        AddNewItemSQL.Parameters.AddWithValue("@ItemCost", Convert.ToInt32(txtItemCost.Text))
        AddNewItemSQL.Parameters.AddWithValue("@ItemCode", txtItemCost.Text.ToString.ToUpper)

        Dim ItemId As Integer

        ItemId = AddNewItemSQL.ExecuteScalar()

        AddNewItemSQL.ExecuteNonQuery()

        conn.Close()

        conn.Open()

        AddNewItemSQL = New SqlCommand(AddNewItem2Comm, conn)

        AddNewItemSQL.Parameters.AddWithValue("@ItemID", ItemId)
        AddNewItemSQL.Parameters.AddWithValue("@ProjectID", Convert.ToInt32(Session("ProjectID")))
        AddNewItemSQL.Parameters.AddWithValue("@ItemQuantity", Convert.ToInt32(txtItemQuantity.Text))

        AddNewItemSQL.ExecuteNonQuery()

        conn.Close()



    End Sub

推荐答案

首先为什么要在多个语句中执行此操作?为什么不:

Why are you doing this in multiple statements in the first place? Why not:

INSERT dbo.Items (item_name,  item_cost, item_code) 
  OUTPUT inserted.ItemID, @ProjectID, @ItemQuantity 
  INTO dbo.project_items(item_id, project_id, item_quantity)
VALUES (@ItemName, @ItemCost, @ItemCode);

现在您只需调用一个 ExecuteNonQuery() 并且您的应用程序不必关心实际生成的 SCOPE_IDENTITY() 值.(当然，您仍然可以检索 SCOPE_IDENTITY()，当然，使用 ExecuteScalar - 但正如 Nenad 正确指出的那样，选择一个而不是同时调用两个.)

Now you only have to call one ExecuteNonQuery() and your app doesn't have to care about the actually SCOPE_IDENTITY() value generated. (You can still retrieve SCOPE_IDENTITY() if you want, of course, using ExecuteScalar - but as Nenad rightly points out, pick one instead of calling both.)

既然我们现在知道这里有一个显式的外键，即使我们不能使用 OUTPUT 子句，我们仍然可以将您的 C# 代码减少到一次调用.

Since we now know that there is an explicit foreign key here, we can still reduce your C# code to one call even if we can't use the OUTPUT clause.

DECLARE @i INT;

INSERT dbo.Items (item_name,  item_cost, item_code) 
  SELECT @ItemName, @ItemCost, @ItemCode;

SELECT @i = SCOPE_IDENTITY();

INSERT dbo.project_items(item_id, project_id, item_quantity)
  SELECT @i, @ProjectID, @ItemQuantity 

SELECT @i; -- if necessary

将其放入存储过程会更简洁.

Would be even cleaner to put this into a stored procedure.

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