I'd like to use the rank() function PostgreSQL on one of my columns.
我想在我的一列上使用rank()函数PostgreSQL。
Character.select("*, rank() OVER (ORDER BY points DESC)")
But since I don't have a rank column in my table rails doesn't include it with the query. What would be the correct way to get the rank included in my ActiveRecord object?
但是由于我的表中没有rank列，所以rails不将它包含在查询中。在我的ActiveRecord对象中包含秩的正确方法是什么?
1 个解决方案
#1
3
try this:
试试这个:
Character.find_by_sql("SELECT *, rank() OVER (ORDER BY points DESC) FROM characters")
it should return you Character objects with a rank attribute, as documented here. However, this may not be database-agnostic and tends to get messy if you pass around the objects.
它应该返回带有rank属性的字符对象，如这里所示。然而，这可能与数据库无关，并且如果您在对象周围传递，会变得很混乱。
another (expensive) solution is to add a rank column to your table, and have a callback recalculate all records' rank using .order whenever a record is saved or destroyed.
另一种(昂贵的)解决方案是向表中添加rank列，并在保存或销毁记录时使用.order重新计算所有记录的秩。
edit :
编辑:
another idea suitable for single-record queries can ben seen here
另一个适合单记录查询的想法可以在这里看到
#1
3
try this:
试试这个:
Character.find_by_sql("SELECT *, rank() OVER (ORDER BY points DESC) FROM characters")
it should return you Character objects with a rank attribute, as documented here. However, this may not be database-agnostic and tends to get messy if you pass around the objects.
它应该返回带有rank属性的字符对象，如这里所示。然而，这可能与数据库无关，并且如果您在对象周围传递，会变得很混乱。
another (expensive) solution is to add a rank column to your table, and have a callback recalculate all records' rank using .order whenever a record is saved or destroyed.
另一种(昂贵的)解决方案是向表中添加rank列，并在保存或销毁记录时使用.order重新计算所有记录的秩。
edit :
编辑:
another idea suitable for single-record queries can ben seen here
另一个适合单记录查询的想法可以在这里看到