I'm designing a table in SQL Server 2008 that will store a list of users and a Google Maps co-ordinate (longitude & latitude).
Will I need two fields, or can it be done with 1?
What's the best (or most common) data-type to use for storing this kind of data?
Take a look at the new Spatial data-types that were introduced in SQL Server 2008. They are designed for this kind of task and make indexing and querying much easier and more efficient.
More information:
I don't know the answer for SQL Server but...
In MySQL save it as FLOAT( 10, 6 )
This is the official recommendation from the Google developer documentation.
CREATE TABLE `coords` (
`lat` FLOAT( 10, 6 ) NOT NULL ,
`lng` FLOAT( 10, 6 ) NOT NULL ,
) ENGINE = MYISAM ;
SQL Server has support for spatial related information. You can see more at http://www.microsoft.com/sqlserver/2008/en/us/spatial-data.aspx.
Alternativly you can store the information as two basic fields, usually a float is the standard data type reported by most devices and is accurate enough for within an inch or two - more than adequate for Google Maps.
If you are just going to substitute it into a URL I suppose one field would do - so you can form a URL like
http://maps.google.co.uk/maps?q=12.345678,12.345678&z=6
but as it is two pieces of data I would store them in separate fields
Store both as float, and use unique key words on them.i.em
create table coordinates(
coord_uid counter primary key,
latitude float,
longitude float,
constraint la_long unique(latitude, longitude)
);