mySql case select - which field to choose

[sd1]

Hello all.
In my database i have some fields:

reg2year
reg5year
reg10year

i want to build a query that will select one of those fields according to a value that was posted from a form in a variable named: $regType.

i need to do this selection in my query and not over the php code.

any ideas?

[laserlight]

After you have validated $regType, try something along the lines of:
SELECT $regType FROM tablename;