变量名为 conn 的 SqlConnection 对象连接到本地 SQL Server 2000 的 Northwind 实例。该实例中包含表 Orders 。为了从 Orders 表查询所有 CustomerID 等于“ tom ”的订单数据,请用正确的字符串 sqlstr 的赋值语句替换下列第一行语句。 string sqlstr=" 本字符串需要你用正确的 SQL 语句替换 ": conn.Open(); SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = sqlstr; cmd.CommandType = CommandType.Text; SqlParameter p1 = cmd.Parameters.Add("@CustomerID",SqlDbType.VarChar,5); p1.Value = "tom"; SqlDataReader dr = cmd.ExecuteReader();
A.
string sqlstr="Select * From Orders where CustomerID=?";
B.
string sqlstr="Select * From Orders where CustomerID=CustomerID ";
C.
string sqlstr="Select * From Orders where customerID=@CustomerID ";
D.
string sqlstr="Select * From Orders";