LEFT join Template

LEFT join Template.sql

--A LEFT join example. 
-- Join two aliased table on two keys they share in common
-- Further filtering via 'and' commands.  

--1. 
select * from modem m
left join camera c
on m.modem_id = c.modem_id
left join camera_value cv
on c.camera_id = cv.camera_id
where m.user_id = 1
and cv.camera_setting_id = 40
and cv.value = 'SuperCam'


--2.  A simple table joined to compare modem ownershipt
-- Since the common link between the two tables was ambigoulsy named 'SN'
-- each were then aliased to make readiblility better.  
--  <<index.key>> AS 'NAME', 
-- Does anyone own this modem?

SELECT sm.SN as 'SN_MEID Table SN', mo.SN as 'Modem Table SN', sm.meid as 'Associated MEID'     
FROM SN_MEID SM
LEFT JOIN modem mo
ON sm.SN = mo.SN

--3.  Another example, lots of columns cited.  
-- Also what I like about this is the bottom >- filter, as I wante a certain set of audits to look up.  
SELECT audit_id, al.audit_type, user_id, admin_id, description, message, update_on     
FROM audit_log al
LEFT JOIN audit_log_type alt
ON al.audit_type = alt.audit_type
WHERE audit_id >= '45'