Question

我有那段代码：

string query = "select count(*) 
                  from MODEL m 
                  join KOLEKCJA ko on m.SEZON = ko.sezon 
             left join PRODUCENCI p on p.PRODUCENT_ID = m.PRODUCENT_ID 
             left join KRAJ k on k.KOD = m.KRAJ_POCH 
                 where ko.SEZON like :ko.SEZON 
                   and m.DO_PRODUKCJI like :m.DO_PRODUKCJI 
                   and k.KOD like :KOD 
                   and p.PRODUCENT_ID like :PRODUCENT_ID 
                   and m.MODEL_ID like :MODEL_ID";

OdbcCommand comm = new OdbcCommand();
comm.Connection = con;
comm.CommandText = query;
comm.CommandType = CommandType.Text;
comm.Parameters.AddWithValue("ko.SEZON", sezon);
comm.Parameters.AddWithValue("m.DO_PRODUKCJI", do_produkcji);
comm.Parameters.AddWithValue("KOD", kraj);
comm.Parameters.AddWithValue("PRODUCENT_ID", fabryka);
comm.Parameters.AddWithValue("MODEL_ID", model);

result = (int)comm.ExecuteScalar();

并始终存在参数未更改的错误; / 我错了什么？

Answer 1

您需要使用占位符来使AddWithValue起作用。以下是MSDN示例的摘录：

private static void UpdateDemographics(Int32 customerID,
    string demoXml, string connectionString)
{
    // Update the demographics for a store, which is stored 
    // in an xml column. 
    string commandText = "UPDATE Sales.Store SET Demographics = @demographics "
        + "WHERE CustomerID = @ID;";

    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        SqlCommand command = new SqlCommand(commandText, connection);
        command.Parameters.Add("@ID", SqlDbType.Int);
        command.Parameters["@ID"].Value = customerID;

        // Use AddWithValue to assign Demographics.
        // SQL Server will implicitly convert strings into XML.
        command.Parameters.AddWithValue("@demographics", demoXml);

        try
        {
            connection.Open();
            Int32 rowsAffected = command.ExecuteNonQuery();
            Console.WriteLine("RowsAffected: {0}", rowsAffected);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
}

Answer 2

ODBC连接不像其他连接类型那样使用命名占位符。 ODBC使用由问号（？）标记的位置参数。用问号替换绑定变量，并确保以正确的顺序添加参数。传递给AddWithValue（）的参数名称可以是任何内容。像这样：

string query = "select count(*) 
                  from MODEL m 
                  join KOLEKCJA ko on m.SEZON = ko.sezon 
             left join PRODUCENCI p on p.PRODUCENT_ID = m.PRODUCENT_ID 
             left join KRAJ k on k.KOD = m.KRAJ_POCH 
                 where ko.SEZON       like ? 
                   and m.DO_PRODUKCJI like ? 
                   and k.KOD          like ? 
                   and p.PRODUCENT_ID like ? 
                   and m.MODEL_ID     like ?";

OdbcCommand comm = new OdbcCommand();
comm.Connection = con;
comm.CommandText = query;
comm.CommandType = CommandType.Text;
comm.Parameters.AddWithValue("ko.SEZON", sezon);
comm.Parameters.AddWithValue("m.DO_PRODUKCJI", do_produkcji);
comm.Parameters.AddWithValue("KOD", kraj);
comm.Parameters.AddWithValue("PRODUCENT_ID", fabryka);
comm.Parameters.AddWithValue("MODEL_ID", model);

result = (int)comm.ExecuteScalar();

Answer 3

您确定您可以使用名称为“ko.SEZON”的参数，即“。”在名字里？尝试删除“。”从两个名称的出现（查询和“AddWithValue”）。

参数不在sql语句中更新

3 个答案: