Question

在网络项目中，我尝试执行以下查询：

SELECT ItemName as Name,
       ItemPicture as Picture,
       ItemHeroModif as Assistance,
       ItemTroopModif as Charisma,
       HerbCost as Herbs,
       GemCost as Gems
FROM Item WHERE ItemId = @value0

使用断点，我可以看到我附加了@value0值2。

尽管如此，我收到以下错误：

没有给出一个或多个必需参数的值。

我知道这个错误通常是由于错误的SQL语法而产生的。我做了什么有什么不对吗？

修改：

附件代码：

var madeForCommand = "SELECT ItemName as Name,ItemPicture as [Picture],ItemHeroModif as Assistance,ItemTroopModif as Charisma, HerbCost as Herbs, GemCost as Gems FROM Item WHERE ";
OleDbCommand command = new OleDbCommand();
for (int ii = 0; ii < items.Count; ii++)// items is a list of items with IDs I want to get from the query.
{
    madeForCommand += "ItemId =@value"+ii+" OR ";   
}
madeForCommand = madeForCommand.Substring(0, madeForCommand.Length - 4); // making sure I trim the final or; In the case I shown, it's just one item, so there are none at all.

后来：

OleDbCommand forOperations = new OleDbCommand(madeForCommand, _dbConnection); //_dbConnection is the connection to the database, it seems to work pretty well.
for (int ii = 0; ii < items.Count; ii++) 
{
    string attach = "@value" + ii;
    command.Parameters.AddWithValue(attach, items[ii].ID);
}

我非常确定items[ii].ID很好，断点显示它等于2且附件顺利。

编辑2 ：我编写了Krish和Hans建议的代码，我得到了以下查询，没有任何附件：

SELECT ItemName as [Name],ItemPicture as Picture,ItemHeroModif as Assistance,ItemTroopModif as Charisma, HerbCost as Herbs, GemCost as Gems FROM [Item] WHERE (ItemID in (2));

如果它发生任何变化，我仍会得到同样的错误。

编辑3 ：在Access中执行查询要求我给参数＆＃34; ItemPicture＆＃34; ...奇数; ItemPicture是一个专栏，不是吗？

Answer 1

Access查询中的

Name，Item和Picture为problem words。将它们括在方括号中：

SELECT ItemName as [Name], ItemPicture as [Picture], ItemHeroModif as Assistance, ItemTroopModif as Charisma, HerbCost as Herbs, GemCost as Gems
FROM [Item] WHERE ItemID in (2);

由于包围这些名称仍然会给您一个缺失的参数投诉，我请求您在Access＆＃39;中测试该查询。查询设计师。在该上下文中，Access提供了一个参数输入框，其中还包括Access将其解释为参数的单词。

您报告Access认为 ItemPicture 是一个参数。因此，通过在Access Design View中检查该表，您发现实际的字段名称为 ItemImageURL 。

SELECT ItemName as [Name], ItemImageURL as [Picture], ItemHeroModif as Assistance, ItemTroopModif as Charisma, HerbCost as Herbs, GemCost as Gems
FROM [Item] WHERE ItemID in (2);

Answer 2

您没有从应用程序外部获取Where条件，因此字符串连接是安全的。（至少我是这么认为的）

只需添加如下参数：

var madeForCommand = "SELECT ItemName as Name,ItemPicture as Picture,ItemHeroModif as Assistance,ItemTroopModif as Charisma, HerbCost as Herbs, GemCost as Gems " +
    "FROM Item WHERE (ItemID in (";
     OleDbCommand command = new OleDbCommand();
     for (int ii = 0; ii < items.Count; ii++)// items is a list of items with IDs I want to get from the query.
     {
          if (i<=1) {
              madeForCommand += items[ii].ID
          }else {
              madeForCommand += "," + items[ii].ID;
          }
     }
    madeForCommand += "))"

最后你将得到一个SQL查询：

"SELECT ItemName as Name,ItemPicture as Picture,ItemHeroModif as Assistance,ItemTroopModif as Charisma, HerbCost as Herbs, GemCost as Gems " +
"FROM Item WHERE (ItemID in (1,2,3))";

Answer 3

MS Access不知道这样的参数：@value0！

使用?代替named parameters，如下所示：

PARAMETERS [value0] INT;
SELECT ItemName as Name,
       ItemPicture as Picture,
       ItemHeroModif as Assistance,
       ItemTroopModif as Charisma,
       HerbCost as Herbs,
       GemCost as Gems
FROM Item WHERE ItemId = [value0];

如何调用此查询？请阅读：Accessing Microsoft Office Data from .NET Applications
有关详细信息，请参阅：OleDbCommand.Parameters Property

<强> [编辑]

根据我的理解，您希望将多个ItemId传递给查询。所以，你必须使用IN子句：

SELECT ...
FROM ...
WHERE ItemID IN (1, 2, 5, 8)

访问SQL查询缺少更多必需参数

3 个答案: