Consulta MySQL Sumar distintas tablas

[quimfv]

Código MySQL:

SELECT Sbc.`START`, 
       SUM(Sbc.Erlangs_voz_hpcs) AS Suma_total, 
       SUM(Sbc.Mbps_DL_hpps) AS Suma_total, 
       SUM(Sbc.Mbps_UL_hpps) AS Sum_total2
FROM (SELECT `START`, 
            SUM(trafico_voz) AS Erlangs_voz_hpcs,
            0 AS Mbps_DL_hpps,
            0 AS Mbps_UL_hpps
     FROM Estadisticas_UMTS.RAN_UCELL_hpcs
     WHERE `START`>=('2014-03-01') 
     GROUP BY `START`
     UNION
     SELECT `START`, 
            SUM(AMR_Traffic) AS Erlangs_voz_hpcs,
            0 AS Mbps_DL_hpps,
            0 AS Mbps_UL_hpps
     FROM Estadisticas_UMTS.KPI_Trafico_cell_hpcs
     WHERE `START`>=('2014-03-01') 
     GROUP BY `START`
     UNION 
     SELECT `START`,
            0 AS Erlangs_voz_hpcs,
            SUM(trafico_datos_R99_DL+trafico_datos_HSDPA)*8/3600 AS Mbps_DL_hpps,
            SUM(trafico_datos_R99_UL+trafico_datos_HSUPA)*8/3600 AS Mbps_UL_hpps
     FROM Estadisticas_UMTS.RAN_UCELL_hpps 
     WHERE `START`>=('2014-03-01') 
     GROUP BY `START`
     UNION
     SELECT `START`,
            0 AS Erlangs_voz_hpcs,
            SUM(DL_PS_R99_Bytes+HSDPA_RLC_Traffic)/1024/1024*8/3600 AS Mbps_DL_hpps, 
            SUM(UL_PS_R99_Bytes+HSUPA_RLC_Traffic)/1024/1024*8/3600 AS Mbps_UL_hpps
     FROM Estadisticas_UMTS.KPI_Trafico_cell_hpps  
     WHERE `START`>=('2014-03-01') 
     GROUP BY `START`) Sbc
GROUP BY Sbc.`START`
 

Las subquery que integran una query de union deben tener los mismos campos... por eso los añado con valor fijo cero (0).

start es una palabra reservada o casi.... inicia el servidor!!!! Usa `start` o cambia el nombre del campo.