Question

我想过滤掉小于3的结果，但每当我添加WHERE语句时，查询都会失败。我的查询有什么问题？我正在使用MySQL Workbench 3.7

SELECT c.name, COUNT(DISTINCT s.product_id) AS veggies  
FROM sales AS s
INNER JOIN customers AS c
ON c.id=s.customer_id
GROUP BY s.customer_id
WHERE veggies > 2"

谢谢！约尼

Answer 1

where应为having：

SELECT c.name, COUNT(DISTINCT s.product_id) AS veggies
FROM sales s INNER JOIN
     customers c
     ON c.id = s.customer_id
GROUP BY s.customer_id
HAVING veggies > 2;

您的查询生成语法错误（即未运行）或在GROUP BY停止并忽略WHERE。

Answer 2

需要在HAVING之后使用GROUP BY而不是WHERE：

SELECT 
    c.name, COUNT(DISTINCT s.product_id) AS veggies
FROM 
    sales AS s
    INNER JOIN customers AS c ON c.id = s.customer_id
GROUP BY 
    s.customer_id
HAVING 
    veggies > 2

Answer 3

Grouping requires knowledge of entire list. There is an order of operations in mysql query。（点击此链接将显示回答该页面的页面）

这很有希望，

SELECT c.name, COUNT(DISTINCT s.product_id) AS veggies'  
FROM sales AS s
INNER JOIN customers AS c
ON c.id=s.customer_id
WHERE veggies > "2"
GROUP BY s.customer_id

交换这两行。

GROUP BY s.customer_id
WHERE veggies > "2"

GROUP BY始终位于WHERE之后。

除此之外，你在这里错过了2左右的开场报价。

WHERE veggies > 2"

在第一行末尾有一个不必要的单引号（'）。

SQL WHERE不会过滤我的结果

3 个答案: