sql - 需要有关SQL查询的帮助

假设我有2张桌子:

Person

 - Id
 - Name

PersonAttribute

 - Id
 - PersonId
 - Name
 - Value

此外，假设每个人都有2个属性(例如，性别和年龄)。样本记录如下:

Person->Id = 1
Person->Name = 'John Doe'

PersonAttribute->Id = 1
PersonAttribute->PersonId = 1
PersonAttribute->Name = 'Gender'
PersonAttribute->Value = 'Male'

PersonAttribute->Id = 2
PersonAttribute->PersonId = 1
PersonAttribute->Name = 'Age'
PersonAttribute->Value = '30'

问题:如何查询此结果，这样的结果:

'John Doe'，'Male'，'30'

最佳答案

SELECT p.name, p1.Value, p2.Value
     FROM Person p, PersonAttribute p1, PersonAttribute p2
     WHERE p.Id = p1.PersonId AND p.Id = p2.PersonId
        AND p1.Name = 'Gender' AND p2.Name = 'Age'