můžete zkusit toto
SELECT ( CASE WHEN ps_month = '04' THEN ps_target_ecpm
ELSE 0
END ) AS april_target_ecmp
,( CASE WHEN ps_month = '04' THEN ps_actual_ecpm
ELSE 0
END ) AS april_actual_ecpm
,( CASE WHEN ps_month = '03' THEN ps_target_ecpm
ELSE 0
END ) AS march_target_ecmp
,( CASE WHEN ps_month = '03' THEN ps_actual_ecpm
ELSE 0
END ) AS march_actual_ecpm
FROM publisher_stats
JOIN domain
ON domain.dmn_id = ps_dmn_id
LEFT JOIN langue
ON langue.lng_id = domain.default_lng_id