Question

我正在尝试从ms访问数据库中获取一个列的总和，但所以没有任何工作，这就是我所拥有的

      Conn.Open();
            Command.CommandText = "Select SUM(c_qty) from COLLVAULT_COINS WHERE c_type!='US Currency' AND c_type!='World Currency' AND c_type!='World Coins' AND c_listName = '" + activeCollection + "'";
            int total_1 = Convert.ToInt32(Command.ExecuteScalar());
            //total sum - get how many match the query
            lblcollectedcount.Text = Convert.ToString(total_1);
            Conn.Close();

任何帮助都会很好。

Answer 1

您可以尝试这样的方法，假设您需要与查询匹配的记录数量：

Conn.Open();
Command.CommandText = "Select SUM(c_qty) as sum, Count(*) as count from COLLVAULT_COINS WHERE c_type <> 'US Currency' AND c_type <> 'World Currency' AND c_type <> 'World Coins' AND c_listName = '" + activeCollection + "'";    //

int total_matches = 0;

using (MySqlDataReader dataReader = Command.ExecuteReader())
{
    if (dataReader.Read()) 
    {
        lblcollectedcount.Text = Convert.ToString(dataReader["sum"]);
        total_matches = Convert.ToInt32(dataReader["count"]);
    } 
    else 
    {
        //nothing was read, handle that case
    }
}

Conn.Close();

编辑：

误解了OP要求的内容，而且我也没有抓住'＆lt;＆gt;'错误。

我仍然会在这里保留这个答案，仅供参考代码使用。

Answer 2

      Conn.Open();
            Command.CommandText = "Select SUM(c_qty) from COLLVAULT_COINS WHERE c_type <>'US Currency' AND c_type<>'World Currency' AND c_type<>'World Coins' AND c_listName = '" + activeCollection + "'";
            int total_1 = Convert.ToInt32(Command.ExecuteScalar());
            //total records
            lblcollectedcount.Text = Convert.ToString(total_1);
            Conn.Close();

我不得不使用＆lt;＆gt;不等于！=

如何从c＃中获取ms访问数据库中的列数

2 个答案: