the idea is this, I need the macro to change my data and set as the days months and year. i have 44 dataset are called like this:   Acr_maestro_mes_ant_20150131 Acr_maestro_mes_ant_20150331 Acr_maestro_mes_ant_20150430 ..................................................... Acr_maestro_mes_ant_20160931 Acr_maestro_mes_ant_20161030   I need the macro to change the date i would not have to create such a long consultation. I did the following:     %MACRO COSECHA; %LET DIA = ; %DO año = 15 %TO 16; %DO MES = 01 %TO 12; %IF ("&MES" = 01 OR "&MES" = 03 or "&MES" = 05 OR "&MES" =07 OR "&MES" = 08 OR "&MES" = 09 OR "&MES" = 12) %THEN "&DIA" = 31; %IF ("&MES" = 04 OR "&MES" = 06 or "&MES" = 10 OR "&MES" =11) %THEN "&DIA" = 30;     data  prueba.Acr_maestro_"$MES$AÑO";     set prueba.Acr_maestro_mes_ant_"&AÑO&MES&DIA";     where LLAMADA= 1;     keep ID LLAMADA SOLICITUD FECHA;     %END;     I`m sure that something is missing in the query, this is the first time that i work with macros in SAS, if you can help me i would appreciate. Sorry for my bad english.   ... View more