mySQL查询中的输出错误

Question

我对mySQL和phpMyAdmin比较陌生，我遇到的问题是我试图输入。我希望“售出的单位”是一个数字，但是整个列打印出“已售出的单位”某些原因。我已经尝试删除两个“售出单位”，我试图删除一个，但我不知道这里出了什么问题。对不起，如果我不够清楚，但这是我的疑问：

SELECT brand_name, brand_type, Round(avgprice,2) AS "Average Price", "Units Sold"
FROM lgbrand b JOIN (SELECT brand_id, Avg(prod_price) AS avgprice 
            FROM lgproduct 
            GROUP BY brand_id) sub1 
ON b.brand_id = sub1.brand_id
    JOIN (SELECT brand_id, Sum(line_qty) AS "Units Sold" 
    FROM lgproduct p JOIN lgline l ON p.prod_sku = l.prod_sku 
GROUP BY brand_id) sub2
    ON b.brand_id = sub2.brand_id
ORDER BY brand_name;

这是一张与输出结果一致的图片：

Answer 1

你非常接近：

SELECT 
   brand_name, brand_type, 
   round(avgprice,2) AS "Average Price", sub2.Units_Sold AS "Units Sold" 
FROM lgbrand b JOIN (SELECT brand_id, Avg(prod_price) AS avgprice 
        FROM lgproduct 
        GROUP BY brand_id) sub1 
ON b.brand_id = sub1.brand_id
JOIN (SELECT brand_id, Sum(line_qty) AS Units_Sold 
     FROM lgproduct p JOIN lgline l ON p.prod_sku = l.prod_sku 
GROUP BY brand_id) sub2
ON b.brand_id = sub2.brand_id
ORDER BY brand_name;

Answer 2

在mySQL中，您应该使用反引号`来表示列和表名。在这里，mySQL将“Units Sold”视为您身边的变量，这就是为什么在结果中将其打印出来的原因。

SELECT b.`brand_name`, b.`brand_type`, Round(sub1.`avgprice`, 2) AS "Average Price", sub2.`Units Sold`
FROM lgbrand b JOIN (SELECT `brand_id`, Avg(`prod_price`) AS avgprice 
            FROM lgproduct 
            GROUP BY `brand_id`) sub1 
ON b.`brand_id` = sub1.`brand_id`
    JOIN (SELECT `brand_id`, Sum(`line_qty`) AS "Units Sold" 
    FROM lgproduct p JOIN lgline l ON p.`prod_sku` = l.`prod_sku` 
GROUP BY `brand_id`) sub2
    ON b.`brand_id` = sub2.`brand_id`
ORDER BY `brand_name`;

Answer 3

如果你想在你的名字中保留空格，请使用：

  SELECT brand_name, brand_type, Round(avgprice,2) AS "Average Price", `Units Sold`
FROM lgbrand b JOIN (SELECT brand_id, Avg(prod_price) AS avgprice 
            FROM lgproduct 
            GROUP BY brand_id) sub1 
ON b.brand_id = sub1.brand_id
    JOIN (SELECT brand_id, Sum(line_qty) AS "Units Sold" 
    FROM lgproduct p JOIN lgline l ON p.prod_sku = l.prod_sku 
GROUP BY brand_id) sub2
    ON b.brand_id = sub2.brand_id
ORDER BY brand_name;

在postgres和Oracle中你可以做＆＃34; fieldname＆＃34;在Mysql中使用