CODEWITHSUNDEEP
sql-serverentity-framework-4.1ef-code-first
wil
wil

Reputation: 2137

C# Float to Real in SQL Server

I am attempting to use Entity Framework and have a contact database that has Longitude and Latitude data from Google Maps.

The guide says that this should be stored as float.

I have created my POCO entity which includes Longitude as a float and Latitude as a float.

I have just noticed that in the database, these both come up as real.

There is still a lot of work to be done before I can get any data back from Google, I am very far away from testing and I was just wondering if anyone can tell me if this is going to be a problem later on?

Upvotes: 3

Views: 3755

Answers (2)

Mike Chamberlain
Mike Chamberlain

Reputation: 42510

This link:

http://msdn.microsoft.com/en-us/library/aa258876(v=sql.80).aspx

explains that, in SQL Server, real is a synonym for float(24), using 4 bytes of data. In .NET a Single precision floating point number also uses 4 bytes, so these are pretty much equivalent:

http://msdn.microsoft.com/en-us/library/47zceaw7(v=vs.71).aspx

Upvotes: 2

Jon Skeet
Jon Skeet

Reputation: 1502716

Nope, that should be fine. Note that you may not get the exact same value back as you received from Google Maps, as that would have been expressed in decimal-formatted text. However, this is effectively a physical quantity, and thus more appropriate as a float/double/real/(whatever binary floating point type you like) than as a decimal. (Decimals are more appropriate for man-made quantities - particularly currency.)

If you look at the documentation for float and real you'll see that real is effectively float(24) - a 32-bit floating binary point type, just like float in C#.

EDIT: As noted in comments, if you want more than the significant 7-8 digits of accuracy provided by float, then you probably want double instead in C#, which would mean float(53) in SQL Server.

Upvotes: 6

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