How to retrieve data from mysql database joining 5 different tables - php

Question

I am trying to retrieve data from mysql database from 5 different table but it did not work as it should and it did not display anything.
tables are :
site_info
site_coordinates
owner_info
subcontractor_info
company_info
site_info:
siteID
companyID
-siteNAME
ownerID
subcontractorID
equipmentTYPE
site coordinates:
siteID
latitude
longitude
height
owner_info:
ownerID
ownerNAME
ownerCONTACT
subcontractor_info:
subcontractorID
subcontractorCOMPANY
subcontractorNAME
subcontractorCONTACT
company_info:
companyID
companyNAME
mysql query:
select
site_info.siteID,site_info.siteNAME ,site_info.equipmentTYPE,site_coordinates.latitude,site_coordinates.longitude,site_coordinates.height ,owner_info.ownerNAME,owner_info.ownerCONTACT,company_info.companyNAME,subcontractor_info.subcontractorCOMPANY,subcontractor_info.subcontractorNAME,subcontractor_info.subcontractorCONTACT
from `site_info`
INNER JOIN `owner_info`
on site_info.ownerID = owner_info.ownerID
INNER JOIN `company_info`
on site_info.companyID = company_info.companyID
INNER JOIN `subcontractor_info`
on site_info.subcontractorID = subcontractor_info.subcontractorID
INNER JOIN `site_coordinates`
on site_info.siteID=site_coordinates.site_id
where owner_info.ownerID = 159
Where is my error, and is there any better way to do it?

Answer 1

I solve it just needed to change to the LEFT JOIN .
so the updated query looks:
select
site_info.siteID,site_info.siteNAME ,site_info.equipmentTYPE,site_coordinates.latitude,site_coordinates.longitude,site_coordinates.height ,owner_info.ownerNAME,owner_info.ownerCONTACT,company_info.companyNAME,subcontractor_info.subcontractorCOMPANY,subcontractor_info.subcontractorNAME,subcontractor_info.subcontractorCONTACT from `site_info`
LEFT JOIN `owner_info`
on site_info.ownerID = owner_info.ownerID
LEFT JOIN `company_info`
on site_info.companyID = company_info.companyID
LEFT JOIN `subcontractor_info`
on site_info.subcontractorID = subcontractor_info.subcontractorID
LEFT JOIN `site_coordinates`
on site_info.siteID=site_coordinates.siteID
where owner_info.ownerID = 159
thank you for your comments and answers

Answer 2

The Query is syntactically correct. Since you are facing output problems check your Relation Algebra. Are you using the right JOIN conditions between them? If each of the two tables has a common attribute you can perform Natural Join ie without giving conditions, the common attribute will be sorted out and I would write such complex queries using ALIAS 'AS' keyword.
SELECT
site_info.siteID,
site_info.siteNAME,
site_info.equipmentTYPE,
site_coordinates.latitude,
site_coordinates.longitude,
site_coordinates.height,
owner_info.ownerNAME,
owner_info.ownerCONTACT,
company_info.companyNAME,
subcontractor_info.subcontractorCOMPANY,
subcontractor_info.subcontractorNAME,
subcontractor_info.subcontractorCONTACT
FROM `site_info` AS SI JOIN `owner_info` AS OI
ON SI.ownerID = OI.ownerID
JOIN `company_info` AS CI
ON SI.companyID = CI.companyID
JOIN `subcontractor_info` AS SUBI
ON SI.subcontractorID = SUBI.subcontractorID
JOIN `site_coordinates` AS SC
ON SI.siteID=SC.site_id
WHERE owner_info.ownerID = 159;