问一个参数问题

[boystone]

sqlcommand.Parameters.Add这个方法是向sqlcommand实例传参吗，
而Parameters.value作用又是什么呢，能说详细些吗

[AllenTing]

１．示例
[Visual Basic, C#] 以下示例创建一个 SqlCommand 并显示其参数。要完成此操作，需将一个 SqlConnection、一个查询字符串（它是一个 Transact-SQL SELECT 语句）和 SqlParameter 对象的一个数组传递给该方法。

[Visual Basic]
Public Sub CreateMySqlCommand(myConnection As SqlConnection, _
mySelectQuery As String, myParamArray() As SqlParameter)
Dim myCommand As New SqlCommand(mySelectQuery, myConnection)
myCommand.CommandText = "SELECT CustomerID, CompanyName FROM Customers WHERE Country = @Country AND City = @City"
myCommand.UpdatedRowSource = UpdateRowSource.Both
myCommand.Parameters.Add(myParamArray)
Dim j As Integer
For j = 0 To myCommand.Parameters.Count - 1
myCommand.Parameters.Add(myParamArray(j))
Next j
Dim myMessage As String = ""
Dim i As Integer
For i = 0 To myCommand.Parameters.Count - 1
myMessage += myCommand.Parameters(i).ToString() & ControlChars.Cr
Next i
Console.WriteLine(myMessage)
End Sub

[C#]
public void CreateMySqlCommand(SqlConnection myConnection,
string mySelectQuery, SqlParameter[] myParamArray) {
SqlCommand myCommand = new SqlCommand(mySelectQuery, myConnection);
myCommand.CommandText = "SELECT CustomerID, CompanyName FROM Customers WHERE Country = @Country AND City = @City";
myCommand.Parameters.Add(myParamArray);
for (int j=0; j<myParamArray.Length; j++)
{
myCommand.Parameters.Add(myParamArray[j]) ;
}
string myMessage = "";
for (int i = 0; i < myCommand.Parameters.Count; i++)
{
myMessage += myCommand.Parameters[i].ToString() + "\n";
}
MessageBox.Show(myMessage);
}
这是ｍｓｄｎ上的示例，答案是肯定的
２．
下面的示例通过 SqlDataAdapter 中的 SqlParameterCollection 集合创建 SqlParameter 的多个实例。这些参数用于从数据源中选择数据并将数据放在 DataSet 中。此示例假定已经用适当的架构、命令和连接创建了 DataSet 和 SqlDataAdapter。
[Visual Basic]
Public Sub AddSqlParameters()
' ...
' create myDataSet and myDataAdapter
' ...
myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", SqlDbType.VarChar, 80).Value = "toasters"
myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", SqlDbType.Int).Value = 239

myDataAdapter.Fill(myDataSet)
End Sub 'AddSqlParameters
[C#]
public void AddSqlParameters()
{
// ...
// create myDataSet and myDataAdapter
// ...

myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", SqlDbType.VarChar, 80).Value = "toasters";
myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", SqlDbType.Int).Value = 239;
myDataAdapter.Fill(myDataSet);

}
搂住也该明白ｖａｌｕｅ何用了