tsset quarterly data

Dear all,

I want to calculate the GDP growth for the US. I downloaded quarterly GDP data from a database. The data looks as follows:
The date variable was a string variable (called 'name'), so I used
Now 'date' looks the same as name, only now as a long variable. However, if I use tsset date, it will start with all the Q1's from each year, and then use all the Q2's from each year. What I want is to maintain the correct ordering (so I guess if it looked as: '1977 Q1' instead of 'Q1 1977' things would work already.

I want to tsset the data so I can calculate quarterly growth figures. I know how to do so in Excel (using previous cells etc.), however, I was wondering how to do so in Stata.
Any tips?

Kind regards,
Thomas