Unir dos consultas en la misma tabla

[quimfv]

Código MySQL:

SELECT mer_mov.mer_id,
             SUM(IF(mer_mov_tipo = 'E',mer_mov_cant,0)) AS entra, 
             SUM(IF(mer_mov_tipo = 'S',mer_mov_cant,0)) AS sale 
FROM mer_mov 
WHERE mer_id = ".$id."
GROUP BY mer_id;
 

Será esto lo que querias?

o esto para todos los mer_id

Código MySQL:

SELECT mer_mov.mer_id,
             SUM(IF(mer_mov_tipo = 'E',mer_mov_cant,0)) AS entra, 
             SUM(IF(mer_mov_tipo = 'S',mer_mov_cant,0)) AS sale 
FROM mer_mov 
GROUP BY mer_id;