基本的SQL查询设计问题

Question

我想创建一个查询，基本上是这个（不起作用）的equivelant。

SELECT * FROM `categories` AS C AND 
SELECT * FROM `items` AS I AND 
SELECT COUNT(I.id) AS items AND 
SELECT SUM(I.price) AS price; 

我没有使用SQLServer，而是通过PHP使用PDO进行数据库连接。

这是表格。

类别

+----+------------+ 
| id | Category | 
+----+------------+ 
| 1 | First_Cat | 
| 2 | Second_Cat | 
+----+------------+ 

项目

+----+----------+------+-------+ 
| id | category | name | price | 
+----+----------+------+-------+ 
| 1 |  1 | Foo | 1.99 | 
| 2 |  1 | Bar | 2.00 | 
| 3 |  2 | ooF | 0.99 | 
| 4 |  2 | raB | 1.99 | 
+----+----------+------+-------+ 

基于这些表我会期待这些查询结果：

+----+------------+-------+-------+--+ 
| id | category | items | price | | 
+----+------------+-------+-------+--+ 
| 1 | First_Cat |  2 | 3.99 | | 
| 2 | Second_Cat |  2 | 2.98 | | 
+----+------------+-------+-------+--+ 

任何帮助？

Answer 1

您在评论中发布的查询中未加入类别表和项目表的查询。这让我觉得你可以做这样的事情吗？：

SELECT 
    categories.id, 
    categories.Category, 
    COUNT(*) AS items, 
    SUM(items.price) as price 
FROM 
    `categories` 
    JOIN items 
     ON categories.id = items.category 
GROUP BY 
    categories.id, 
    categories.Category