select  
            *  
            from 	fi_simplificadas    
            where  
            
            
            ( fecha_creacion_server > '2019-07-01' )  
        
      and   electronica_resultado	 =  0  
      and   electronica_enviada      =  1 
      and   CHARACTER_LENGTH(consecutivo) = 20   
      and entidad = 
            
                            (select entidad from fi_simplificadas  where 1  
                
                            and ( fecha_creacion_server > '2019-07-01' )  
                            and   electronica_resultado	 = 0  and electronica_enviada = 1 
                            and estado > 0 
                            order by rand()  limit 1  )     limit 20