Creating a SQL query to return values from nominally formed databases

Question

I am attempting to return a report from an appointment database. I have attached my current sql query, the difficulty I am having is that when I "join" my customer contacts table ie

 join contacts on (customer.entity_id = contact.contact_id and contacts.arch = 'contact.phonenumber')
    join contact_detail on (contact_detail.contact_id = contacts.contact_id and contact_detail.lookup = 'mobile')

I immediately lose any clients that didn't have an entry on that table and the detail table, what I would prefer to achieve is that the if the client has no contact entry it returns a null for those fields. ie before I added that join it might have gone

Name  Time note    Mobile
DAVID 8pm haircut  0412656865
Julie 8pm style
Daniel 8pm Colour  0412533535

but with those lines added

DAVID 8pm haircut  0412656865
Daniel 8pm Colour  0412533535

it excludes Julie because she has no contact.phonenumber

Thats the simple question. I would prefer that Julie be returned with a NULL value

This system uses a mysql database with a java archetype driven front end hence we use a entity table, act table, participations and then some detail and lookup tables.

the actual sql query is

select 
p.activity_start_time
, p.activity_end_time
, p.activity_start_time AS start_time
, p.activity_end_time as end_time
, a.status
, a.description AS appointmentnote
, e.name as patientname
, e.description AS patientdescription
, customer.name as customername
, customer.description as customerdescription
, sd.name as schedule_name
, eAt.name as appointment_type
, mobile.description as Mobile
from acts a
join participations p on  
a.act_id=p.act_id and a.arch_short_name='act.customerAppointment' and 
p.act_arch_short_name='act.customerAppointment'
join entities e on p.entity_id=e.entity_id
join participations pAt on a.act_id=pAt.act_id and 
a.arch_short_name='act.customerAppointment' and 
pAt.arch_short_name='participation.appointmentType'
join entities eAt on pAt.entity_id=eAt.entity_id
left join entity_relationships er ON (er.target_id = e.entity_id
AND er.active_start_time <= date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "00:00:00" HOUR_SECOND)
AND ((er.active_end_time >= date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "23:59:59" HOUR_SECOND)) OR (er.active_end_time IS NULL)))
left join entities customer ON 
(customer.entity_id = er.source_id AND customer.arch_short_name = 'party.customerperson')

join contacts mobile on (mobile.party_id = customer.entity_id AND mobile.arch_short_name = 'contact.phoneNumber')
join contact_classifications mb_class on (mb_class.contact_id = mobile.contact_id AND mb_class.lookup_id = '120')

join participations schedule on 
a.act_id=schedule.act_id and schedule.arch_short_name='participation.schedule'
left join entities sd on 
(sd.entity_id = schedule.entity_id)
left outer join act_details d on 
a.act_id=d.act_id
where (p.activity_start_time<date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "00:00:00" HOUR_SECOND)
and p.activity_end_time>date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "23:59:59" HOUR_SECOND) or 
p.activity_start_time<date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "00:00:00" HOUR_SECOND)
and p.activity_end_time>date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "23:59:59" HOUR_SECOND) or 
p.activity_start_time>=date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "00:00:00" HOUR_SECOND) and 
p.activity_end_time<=date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "23:59:59" HOUR_SECOND)) and 
(schedule.activity_start_time<date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "00:00:00" HOUR_SECOND) and 
schedule.activity_end_time>date_add((date_format('2013-07-24',"%Y-%m-%d")),
 INTERVAL "23:59:59" HOUR_SECOND) or 
schedule.activity_start_time<date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "00:00:00" HOUR_SECOND) and 
schedule.activity_end_time>date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "23:59:59" HOUR_SECOND) or 
schedule.activity_start_time>=date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "00:00:00" HOUR_SECOND) and 
schedule.activity_end_time<=date_add((date_format('2013-07-24',"%Y-%m-%d")), 
INTERVAL "23:59:59" HOUR_SECOND)) and 
e.arch_short_name = 'party.patientpet' and 
customer.arch_short_name = 'party.customerperson'
and sd.name like CONCAT('GROOM','%')
order by p.activity_start_time, sd.name, a.act_id

Answer 1

Try it

join contact_detail on (contact_detail.contact_id = contacts.contact_id and (contact_detail.lookup = 'mobile' or contact_detail.lookup = null))

or (it can depend from MySQL syntax)

join contact_detail on (contact_detail.contact_id = contacts.contact_id and (contact_detail.lookup = 'mobile' or contact_detail.lookup is null))