Shell Programming and Scripting

Hi all,
I need to 'create' a new simple scripting language in order to allow SCADA operators make complex tasks against the system in an easy and friendly way.
In other words I need to write mini modules with DB readings or writings, calculations, and so on, but these instructions must be written in a simple scripting language easy to learn by the operators.
For example, this can be a script:
VALUE = OBTAIN (name_of_field)
VALUE2 = OBTAIN (name_of_field2)
RESULT = VALUE1 + VALUE2

something like this
Does anyone know how can I make it?
Someone told me about lexx and yacc. Does anybody know another way?
or another easier tools?
thank you in advance

While "little languages" have a long and honored tradition, perhaps in today's day and age it would be simpler to create a module and/or some glue code for an existing scripting language, and perhaps teach the operators just a strict subset of that language. Implementing the language itself is also a lot easier in a reasonably high-level language. My suggestions would be to look at Python, Perl, or Lua, perhaps roughly in that order; if you have another scripting language which you and/or your operators are already familiar with, include that in the list, too.

How about a character based menu driven interface instead of a new language. Leverage Perl to access/update the database behind the scenes. This way the operators are completely insulated from the details of the particular language or script and all they need to know is which menu option does what tasks.