Question

So I join two tables in a query, let’s use below as an example:

SELECT property.address, property.city, property.state, property.zip, unit.name    
FROM   property, unit
WHERE  unit.propertyID = property.id

This table can return a list of all properties that have a matching unit in the unit table.

My problem is, if I have properties that DO NOT have units, I still want those to show up, with “N/A” or “NULL” or something in place of the unit name…

As of now, it just completely excludes those properties that don’t have at least 1 matching unit.

Any ideas?

Answer 1

Simplest way to update your query to working order:

SELECT property.address, property.city, property.state, property.zip, unit.name    
FROM   property
left join unit on property.id = unit.propertyID

Better way to write it, using aliases:

select p.address, p.city, p.state, p.zip, u.name
from property p
left join unit u on p.id = u.propertyID

To populate a value when there is no unit:

select p.address, p.city, p.state, p.zip, IFNULL(u.name,'N/A') as unitName
from property p
left join unit u on p.id = u.propertyID