为什么我在 MySQL 'UPDATE' 命令上遇到错误？

Question

目前我的类图如下所示：

并且我想更新我的所有产品详细信息（prodName、prodDesc、prodCategory、prodDesc、制造商、供应商、stockLevel、reorderLevel、unitPrice），prodID 除外。

所以我使用了这个 SQL 查询：

UPDATE Product
    SET prodName = @prodName,
        prodCategory = @prodCategory,
        prodDesc = @prodDesc,
        manufacturer = @manufacturer,
        supplier = @supplier,
        stockLevel = @stockLevel,
        reorderLevel = @reorderLevel,
        unitPrice = @unitPrice
FROM product a, supply_item b, supply c
WHERE a.prodID = @prodID AND
      @prodID = b.prodID AND
      b.supplyID = c.supplyID;

但它无法工作，我的查询是否正确？

这是我的代码部分

protected void editSubmit_Click(object sender, EventArgs e)
    {
        MySqlConnection conn = new MySqlConnection(sqlConn);
        string sql = "UPDATE Product SET prodName = @prodName, prodCategory = @prodCategory, prodDesc = @prodDesc, manufacturer = @manufacturer, supplier = @supplier, stockLevel = @stockLevel, reorderLevel = @reorderLevel, unitPrice = @unitPrice FROM product a, supply_item b, supply c WHERE a.prodID = @prodID AND @prodID = b.prodID AND b.supplyID = c.supplyID;";
        MySqlCommand cmd = new MySqlCommand(sql, conn);
        conn.Open();
        cmd.Parameters.AddWithValue("@prodName", txtProductName.Text);
        cmd.Parameters.AddWithValue("@prodCategory", txtCategory.Text);
        cmd.Parameters.AddWithValue("@prodDesc", txtProductDesc.Text);
        cmd.Parameters.AddWithValue("@manufacturer", txtManufacturer.Text);
        cmd.Parameters.AddWithValue("@supplier", txtSupplier.Text);
        cmd.Parameters.AddWithValue("@stockLevel", txtStockLvl.Text);
        cmd.Parameters.AddWithValue("@reorderLevel", txtReorderLvl.Text);
        cmd.Parameters.AddWithValue("@unitPrice", txtPrice.Text);
        cmd.Parameters.AddWithValue("@prodID", txtProductID.Text); 
        cmd.ExecuteNonQuery();
        conn.Close();
    }

最初，我使用了这个查询，

"UPDATE Product SET prodName = @prodName, prodCategory = @prodCategory, prodDesc = @prodDesc, manufacturer = @manufacturer, supplier = @supplier, stockLevel = @stockLevel, reorderLevel = @reorderLevel, unitPrice = @unitPrice WHERE prodID = @prodID" 

但它没有显示任何错误，并且我无法更新我的产品上的任何值 知道如何更新我的产品吗？ 谢谢??????

Answer 1

MySQL 中的等价物似乎是：

UPDATE product p JOIN
       supply_item si 
       ON p.prodId = si.prodId JOIN 
       supply s
       ON s.supplyID = si.supplyID;
    SET p.prodName = @prodName,
        p.prodCategory = @prodCategory,
        p.prodDesc = @prodDesc,
        p.manufacturer = @manufacturer,
        p.supplier = @supplier,
        p.stockLevel = @stockLevel,
        p.reorderLevel = @reorderLevel,
        p.unitPrice = @unitPrice
WHERE p.prodID = @prodID;

注意事项：

• 切勿在FROM 子句中使用逗号。
• 始终使用正确、明确、标准、可读的JOIN语法。
• 使用有意义的表别名（例如表名的缩写），而不是任意字母。