SQL：LEFT OUTER JOIN的帮助

It appears my SQL isn't limiting results based on price.

看来我的SQL不是基于价格限制结果。

In my previous post, SQL: Help me optimize my SQL, people indicated that I should use a LEFT OUTER JOIN.

在我之前的帖子中,SQL:帮助我优化我的SQL,人们表示我应该使用LEFT OUTER JOIN。

SELECT homes.home_id, 
    address, 
    city, 
    state, 
    zip, 
    price, 
    photo_id, 
    photo_url_dir
FROM homes
LEFT OUTER JOIN home_photos ON homes.home_id = home_photos.home_id
AND primary_photo_group_id = home_photo_group_id
AND home_photo_type_id =2
AND display_status = true
AND homes.price BETWEEN 500000 AND 1000000

However, it's still displaying homes whose price is < 500000

I don't understand. Why would the SQL above display homes that have a price less than 500000 when I have a WHERE condition to limit exactly that field.

我不明白。当我有一个WHERE条件来精确限制该字段时,为什么上面的SQL会显示价格低于500000的房屋。

Thanks for your help.

谢谢你的帮助。

What I want to do

I want to display both homes with and homes without a home_photo based on criteria like PRICE between X and Y ... or SQFT > Z. But these criteria needs to be applied to both those homes with and those homes without a home_photo

我希望根据X和Y之间的PRICE或SQFT> Z等条件显示家庭和没有home_photo的家庭。但是这些标准需要应用于那些家庭和没有home_photo的家庭

Is this correct?

SELECT homes.home_id, 
    address, 
    city, 
    state, 
    zip, 
    price, 
    photo_id, 
    photo_url_dir
FROM homes
LEFT OUTER JOIN home_photos ON homes.home_id = home_photos.home_id
    AND homes.primary_photo_group_id = home_photos.home_photo_group_id
    AND home_photos.home_photo_type_id =2
WHERE homes.display_status = true
AND homes.price BETWEEN 500000 AND 1000000

4 个解决方案

#1

the last line should be using WHERE not AND

最后一行应该使用WHERE而不是AND

WHERE homes.price BETWEEN 500000 AND 1000000

The end result is the following SQL:

最终结果是以下SQL:

SELECT 
    homes.home_id, 
    homes.address, 
    homes.city, 
    homes.state, 
    homes.zip, 
    homes.price, 
    home_photos.photo_id, 
    home_photos. photo_url_dir
FROM 
    homes
    LEFT OUTER JOIN home_photos ON 
        homes.home_id = home_photos.home_id
        AND homes.primary_photo_group_id = home_photos.home_photo_group_id
        AND home_photos.home_photo_type_id =2
WHERE
    homes.price BETWEEN 500000 AND 1000000
    AND homes.display_status = true

EDIT

now your SQFT would go before the WHERE

现在你的SQFT将在WHERE之前

AND home_photos.home_photo_type_id =2 
AND SQFT <=2000 
WHERE homes.price BETWEEN 500000 AND 1000000

#2

Use the join conditions after JOIN keyword and all other filter conditions after the WHERE clause

在JOIN关键字之后使用连接条件,在WHERE子句之后使用所有其他过滤条件

#3

Try this...

SELECT homes.home_id,     
address,     
city,     
state,     
zip,     
price,     
photo_id,     
photo_url_dir
FROM 
homes
LEFT OUTER JOIN 
home_photos ON homes.home_id = home_photos.home_id
AND 
primary_photo_group_id = home_photo_group_id
WHERE 
home_photo_type_id =2
AND 
display_status = true
AND 
homes.price BETWEEN 500000 AND 1000000

#4

You have all the conditions in the join, you should have some of them in a where clause to limit the query. Something like:

您拥有连接中的所有条件,您应该在where子句中使用其中一些条件来限制查询。就像是:

select
   homes.home_id, 
   address, 
   city, 
   state, 
   zip, 
   price, 
   photo_id, 
   photo_url_dir
from
   homes
left join
   home_photos on homes.home_id = home_photos.home_id
where
   primary_photo_group_id = home_photo_group_id and
   home_photo_type_id = 2 and
   display_status = true and
   homes.price BETWEEN 500000 AND 1000000

As I don't know which table each field comes from, I don't know if the above makes sense. Divide the conditions between the join and the where as it fits.

由于我不知道每个字段来自哪个表,我不知道上述内容是否有意义。划分连接和适合的位置之间的条件。

#1