mysql - MySQL - 我的 JOIN 查询中的 WHERE 子句有什么问题？

Question

我设法拼凑了一个连接语句，为我提供了一个显示整个数据库的表。现在我需要将结果缩小到最近 30 天，但我一生都无法弄清楚如何将此限制应用于查询。

现在我有：

select customers.name, customers.email, orderinfo.orderno, orderinfo.orderdate, status.state, orderinfo.lastupdate 
from customers 
where orderinfo.orderdate = curdate() 
inner join orderinfo on customers.id=orderinfo.fk_id 
inner join status on orderinfo.fk_code=status.code 
order by customers.name;

...试图缩小范围以向我展示今天的所有记录，但即使这样也行不通。我看到有多种方法可以做 30 天的事情，但我遇到最多的问题就是让 WHERE 子句在这个查询中完全起作用。

感谢您的任何建议！

Answer 1

该WHERE子句需要ORDER BY在所有连接之前和之后。

select customers.name, customers.email, orderinfo.orderno, orderinfo.orderdate, status.state, orderinfo.lastupdate 
from customers 
inner join orderinfo on customers.id=orderinfo.fk_id 
inner join status on orderinfo.fk_code=status.code 
where orderinfo.orderdate = curdate() 
order by customers.name;

Answer 2

你没有orderinfo在你的FROM部分指定。

select customers.name, customers.email, orderinfo.orderno, orderinfo.orderdate, status.state, orderinfo.lastupdate 
from customers 
inner join orderinfo on customers.id=orderinfo.fk_id 
inner join status on orderinfo.fk_code=status.code 
where orderinfo.orderdate = curdate() 
order by customers.name;

Answer 3

SELECT customers.name, customers.email, orderinfo.orderno, orderinfo.orderdate, status.state, orderinfo.lastupdate 
FROM customers 
INNER JOIN orderinfo ON customers.id=orderinfo.fk_id 
INNER JOIN status ON orderinfo.fk_code=status.code 
WHERE orderinfo.orderdate = curdate() 
ORDER BY customers.name;

WHERE毕竟JOINS和之前需要ORDER BY

Answer 4

你的内部连接应该在你的 where 子句之前

select customers.name, customers.email, orderinfo.orderno, orderinfo.orderdate, status.state, orderinfo.lastupdate 
from customers 
inner join orderinfo on customers.id=orderinfo.fk_id 
inner join status on orderinfo.fk_code=status.code 
where orderinfo.orderdate = curdate() 
order by customers.name;

如果您需要先使用条件进行查询，那么您需要子查询

Select * From
(
   select customers.name, customers.email, orderinfo.orderno, orderinfo.orderdate, status.state, orderinfo.lastupdate 
   from customers
   where orderinfo.orderdate = curdate()  
) customers
inner join orderinfo on customers.id=orderinfo.fk_id 
inner join status on orderinfo.fk_code=status.code 
order by customers.name;