DateTime's representation in milliseconds?

Question

I have a SQL-server timestamp that I need to convert into a representation of time in milliseconds since 1970. Can I do this with plain SQL? If not, I\'ve extracted it into

Answer 1

As of .NET 4.6, you can use a DateTimeOffset object to get the unix milliseconds. It has a constructor which takes a DateTime object, so you can just pass in your object as demonstrated below.

DateTime yourDateTime;
long yourDateTimeMilliseconds = new DateTimeOffset(yourDateTime).ToUnixTimeMilliseconds();

As noted in other answers, make sure yourDateTime has the correct Kind specified, or use .ToUniversalTime() to convert it to UTC time first.

Here you can learn more about DateTimeOffset.