Question

I have a table that looks like this:

meta_id post_id     meta_key    meta_value
271     4           _aciudad    New york
270     4           _apais      USA
267     10          _aservicio  Alojamiento

...
261     43          _apais      USA
238     43          _aciudad    Chicago
262     43          _aservicio  Alojamiento
...
261     43          _apais      USA
238     43          _aciudad    Miami
262     43          _aservicio  Alojamiento

I need to display all the entries that match Country > City. Or order all the _aciudad entries by country; something like:

meta_id post_id  meta_key   meta_value       meta_key    meta_value 
235      42      _aciudad        New York     _apais       USA
236      56      _aciudad        Chicago      _apais       USA
237      57      _aciudad        Miami        _apais       USA
238      58      _aciudad        Sidney       _apais      Australia
238      59      _aciudad        Melbourne    _apais      Australia

I have no idea how to do this; I guess with an INNER JOIN?

Answer 1

   SELECT t1.meta_id, 
           t1.post_id, 
           t1.meta_key, 
           t1.meta_value, 
           t2.meta_key, 
           t2.meta_value 
    FROM table t1, table t2  
    WHERE t1.post_id = t2.post_id 
    AND t1.meta_key = '_apais'
    AND t2.meta_key = '_aciudad'
    ORDER BY t1.meta_key