SQL连接具有两种类型的元素的表

Question

I have a table of objects that can have two types:

objects:

id | name | type1 | type2 |
-------------------------
1  | bla  |   5   |   7   |

and a table of types

types:

id | name |
-----------
5  | typ5 |
7  | typ7 |

How could I join them like the following?

object.id | object.name | typename1 | typename2 |
------------------------------------------------

I tried the following, but I obtained two rows per object

SELECT objects.id,objetcs.name,types.name
from objects
INNER JOIN types
ON objects.type1=types._id OR objects.type2=types._id

Answer 1

You need two joins:

SELECT o.id, o.name, t1.name as name1, t2.name as name2
from objects o LEFT OUTER JOIN
     types t1
     ON o.type1 = t1._id LEFT OUTER JOIN
     types t2
     on o.type2 = t2._id;