Question

我是C＃的新手，所以也许我没有正确地做错。

在我的C#表单中，我将order nr.放入表单中。然后在sql。

中进行检查

需要执行此查询：

从OrderID

Order nr.

需要检查Order ID是否在[System_Opened_Orders] =订单已打开
如果订单已打开，则需要在C＃中运行Messagebox.Show("Order opened, try again later")
如果未打开，请从order

SQL查询：


    Declare @OrderID uniqueidentifier
    SET @OrderID = (SELECT m.ID FROM [Agenda].[dbo].[orders] m
    WHERE m.OrderNumber= @sqlordernr)

if EXISTS (SELECT 1 FROM [Agenda].[dbo].[System_Opened_Orders] 
        WHERE Record_ID=@OrderID )
            BEGIN
                  // Tell its opened, need try again later
            END

        ELSE
            BEGIN
                   // Order is not openend, can get custommer data
                   select ID, OrderNumber, CustommerName, CustommerCity
                   FROM [Agenda].[dbo].[orders] where OrderNumber = @sqlordernr
            END

C＃代码：

if EXISTS (SELECT 1 FROM [Agenda].[dbo].[System_Opened_Orders] 
        WHERE Record_ID=@OrderID )
            BEGIN
                  // Tell its opened, need try again later
            END

        ELSE
            BEGIN
                   // Order is not openend, can get custommer data
                   select ID, OrderNumber, CustommerName, CustommerCity
                   FROM [Agenda].[dbo].[orders] where OrderNumber = @sqlordernr
            END

Answer 1

如果“订单已打开”

，则无需选择任何内容

IF EXISTS (SELECT 1 FROM [Agenda].[dbo].[System_Opened_Orders] WHERE Record_ID=@OrderID )
BEGIN
    -- Order is not openend, get custommer data
    select ID, OrderNumber, CustommerName, CustommerCity
    FROM [Agenda].[dbo].[orders] where OrderNumber = @sqlordernr
END

然后在代码方面;如果datareader上没有行，则.Read（）将返回 false

using (SqlDataReader reader = command.ExecuteReader())
{
    while(reader.Read())
    {
       // String OrderCustommerName = reader.GetString(3).TrimEnd();
       // String OrderCustommerCity= reader.GetString(4).TrimEnd();
       // lbOrderData.Text = OrderCustommerName + " " + OrderCustommerCity;
    }
}

Answer 2

您需要从存储过程中的if语句返回一些内容。您只需返回一个值

即可

if EXISTS (SELECT 1 FROM [Agenda].[dbo].[System_Opened_Orders] 
    WHERE Record_ID=@OrderID )
        BEGIN
            select 1 
        END
    ELSE
        BEGIN
           -- Order is not openend, get custommer data
           select ID, OrderNumber, CustommerName, CustommerCity
           FROM [Agenda].[dbo].[orders] where OrderNumber = @sqlordernr
        END

现在你可以看看两个结果之间的区别，看看DataReader的属性FieldCount

using (SqlDataReader reader = command.ExecuteReader())
{
    if (reader.FieldCount == 1)
        MessageBox.Show("Order open");
    else
    {
        while(reader.Read())
        {
           // String OrderCustommerName = reader.GetString(3).TrimEnd();
           // String OrderCustommerCity= reader.GetString(4).TrimEnd();
           // lbOrderData.Text = OrderCustommerName + " " + OrderCustommerCity;
        }
    }
}

带有sql查询结果的C＃到变量

2 个答案: