If you have a string with a series of delimited fields such as:
You can figure out the number of fields in the string by using the POS function to count the number of delimiters.
Count = POS("," = <string>,1,0)
Giving the POS function a increment of 1 with an occurence number of zero causes it to return the count instead of the position.
The only thing to watch for is if the string does not have a trailing delimiter such as "a,b,c" -- in this case the number will be one too low.