Question

我希望SQL代码从数据库中获取Product_name,Sum(quantity),price并在winform上显示给datagridview。到目前为止，我有这段代码来获取数据：

conn.Open();
SqlDataAdapter da = new SqlDataAdapter("SELECT Prod_name, SUM(quantity) AS quantity, Price FROM Fatur GROUP BY Prod_name, Price ", conn);

DataSet ds = new DataSet();
da.Fill(ds);

dataGridView1.DataSource = ds.Tables[0];
conn.Close();

问题1是：如何在乘法 Sum(quantity) * Price AS Total的SQL代码上添加另一列？

我尝试了用上述代码填充 dataGridView1 的另一种方法，并在 dataGridView1 中创建了另一列，该列乘以 quantity 和价格的列。这是代码

foreach(DataGridViewRow row in dataGridView1.Rows)
{
    row.Cells[0].Value = Convert.ToString(Convert.ToInt32(row.Cells[2].Value) * Convert.ToInt32(row.Cells[3].Value));
}

但是它显示了一个空列。

Answer 1

最好在SQL中执行：

SELECT Prod_name,
  SUM(quantity) AS quantity,
  Price,
  SUM(quantity) * Price total
FROM Fatur
GROUP BY Prod_name,
  Price;

OR：

SELECT prod_name,
  quantity,
  price,
  quantity * price total
FROM
  (SELECT Prod_name,
    SUM(quantity) AS quantity,
    Price
  FROM Fatur
  GROUP BY Prod_name,
    Price
  );

Answer 2

尝试在查询中包含计算列，如：

 conn.Open();
 SqlDataAdapter da = new SqlDataAdapter("SELECT Prod_name, SUM(quantity) AS quantity, Price,SUM(quantity)*Price as Total FROM Fatur GROUP BY Prod_name, Price ", conn);
 DataSet ds = new DataSet();
 da.Fill(ds);
 dataGridView1.DataSource = ds.Tables[0];
 conn.Close();

将Sum列与另一列相乘

2 个答案: