mysql - 试图将 avg 转换为小数，语法错误

Question

我正在尝试将我的平均值转换为小数，但出现语法错误:

1064 You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'INT, avg(item_price)) as total_price, count(basket_item) a' at line 4 in

我的数据库:

SELECT 
      item_id, 
      item_name, 
      CONVERT(INT, avg(item_price)) as total_price, 
      count(basket_item) as quantity, 
      item_price 
FROM basket b, items i
WHERE b.basket_user = ? 
AND i.item_id = b.basket_item  
AND i.item_quantity > 0

我也尝试过转换，但遇到了同样的错误，我使用的是 xampp php 7 版本

Answer 1

avg 返回一个 DECIMAL。下面的代码应该可以解决这个问题。

More information on casting

SELECT CAST(2.234 AS UNSIGNED) FROM DUAL;

SELECT 
      item_id, 
      item_name, 
      CAST(avg(item_price) AS UNSIGNED) as total_price, 
      count(basket_item) as quantity, 
      item_price 
FROM basket b, items i
WHERE b.basket_user = ? 
AND i.item_id = b.basket_item  
AND i.item_quantity > 0