[英]mysql order by field name contained in another table field value
I have a search query where i need to order by a field contained in another table field value. 我有一个搜索查询,在这里我需要按另一个表字段值中包含的字段进行排序。 Not very clear perhaps :) 也许不是很清楚:)
Consider this : 考虑一下:
$requete = "
SELECT A.*,
(SELECT payspan FROM Categories WHERE id=A.category_id) AS SortingFieldName
FROM Annonces A
JOIN Categories C ON C.id=A.category_id
WHERE A.deleted=0
ORDER BY SortingFieldName";
I would like to order like this, but it does not work : ORDER BY A.SortingFieldName 我想这样订购,但不起作用: ORDER BY A.SortingFieldName
SortingFieldName will contain the name of the field, but not the value of that field in the Annonce table. SortingFieldName将包含字段的名称,但不包含Annonce表中该字段的值。
How can i get the value of that field and then order by ? 我如何获取该字段的值然后排序?
I tried a variable, but dont seem to be able to use a variable inside a query ... 我尝试了一个变量,但似乎无法在查询中使用变量...
To make it simple, i would like to order Annonces lines by the field configured in Categories. 为简单起见,我想按“类别”中配置的字段对Annonces行进行排序。
Like, if i have in Annonces : id,name,category_id,price_day,price_month 像,如果我在Annonces中:id,name,category_id,price_day,price_month
And in Categories : id,name,pricefield 并且在类别中:id,name,pricefield
I would like to order lines in Annonce with the value of price_month or price_day according to the configuration of the category. 我想根据类别的配置在Nononce中订购价格为price_month或price_day的行。
Thx for any help. 感谢任何帮助。
Use this: 用这个:
ORDER BY CASE SortingFieldName
WHEN 'field1' THEN field1
WHEN 'field2' THEN field2
WHEN 'field3' THEN field3
...
END
Replace field1
, field2
, etc. with the actual field names. 用实际的字段名称替换field1
, field2
等。
If you can't list all the possible field names, you'll have to write use dynamic SQL. 如果无法列出所有可能的字段名称,则必须使用动态SQL编写。
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