将参数添加到命令ADO.NET

Question

我正在尝试使用此代码从db中选择数据：

 getForecastsCommand.CommandText = @"SELECT TOP @Count * FROM Forecasts Order by [ForecastId] DESC";

   var countParam = getForecastsCommand.CreateParameter();
   countParam.ParameterName = "@Count";
   countParam.Value = count;
   countParam.DbType = DbType.Int32;
   getForecastsCommand.Parameters.Add(countParam);

但这不起作用：

Incorrect syntax near '@Count'.

为什么不起作用？

Answer 1

请尝试SELECT TOP (@Count) * FROM Forecasts Order by [ForecastId] DESC

请注意@count被括号括起来。

Answer 2

该语法看起来像Microsoft Access数据库。如果是，则不支持TOP的参数。你必须构建字符串。

@"SELECT TOP " + Count + " * FROM Forecasts Order by [ForecastId] DESC";