PHP MySQL and joining two table results

Hi Experts,

I have two tables that rows are linked by the 'PersonRef' field.

Table 'person' example:
PersonRef FirstName LastName
12 Jim Smith
23 Alex Lewis
34 Linda Smith

Table 'person_meta' example:
PersonRef Field Value
12 Age 24
12 Title Mr
23 Age 24
23 Title Mr
34 Age 24
34 Title Mrs

I am looking for a sql query (mysqli_connect) that would return any person who is 'Age' = '24' and 'LastName' = 'Smith' but in an array with this format:
[0] => array('FirstName'=>'Jim','LastName'=>'Smith','Meta'=>array('Title'=>'Mr','Age'=>'24'))
[1] => array('FirstName'=>'Linda','LastName'=>'Smith','Meta'=>array('Title'=>'Mrs','Age'=>'24'))

So basically searching the two tables and linking the data. Removing PersonRef 23 as they don't have a LastName Smith.

Any help would be gratefully received. I've been going round in circles with Joins.

maccaj51

Asked: 2016-09-17

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1 Solution

LVL 35

Terry WoodsIT GuruCommented: 2016-09-17

Formatting the result would be best put in a separate question. Get the query sorted first, and then worry about formatting the results after that. Try this query:

select FirstName, LastName, MetaTitle.Value Title, MetaAge.Value Age
from person
join person_meta MetaTitle on MetaTitle.PersonRef = person.PersonRef
join person_meta MetaAge on MetaAge.PersonRef = person.PersonRef
where MetaAge.Value = '24'
and LastName = 'Smith'

Open in new window

Note that unless you use left joins (which I haven't), you'll only get a row returned for a person when there exists both a title record in person_meta and an age record in person_meta

LVL 82

arnoldCommented: 2016-09-17

using a case/if statement within the join statement.

Select p.firstname,p.adtname,
(Get the title) as title,
(Get the age) as age
From person p join person_meta f on f.petsonref=p.personref
Where f.field='Age' and f.value=24 and p.lastname='Smith'
Group by p.lastname,p.firstname

This way if one is missing, you would still get the results.

LVL 82

arnoldCommented: 2016-09-17

Here is the reference to case
https://dev.mysql.com/doc/refman/5.7/en/case.html

For age
(Case
When f.field='Age' then f.value
Else ''
End case) as Age
For Title
(Case
When f.field='Title' then f.value
Else ' '
End case) As Title

If mo title, you will get an empty string in the corresponding column, but if there is no Age, your query will return no values.

maccaj51Author Commented: 2016-09-18

Thanks very much.

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PHP MySQL and joining two table results

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