Set Varible Using Code (Rawset?)

How can I set a varible in code for example i want to make a varible called vaild. Its uses a string and another varible to make it…

local vaild = "vaild-" .. id

How can I do this… It has always returned an error…

Can I use rawset?

variable = "testVariable"
anotherVariable = ("test"..variable)
print(anotherVariable)

This will return:
test testVariable

Im almost certain this will work

What was the type of id?

was the error attempt to concatenate string and [something else], if it was then the type of id was not a string so it couldn't join them, fix = 'local valid = "valid-"..tostring( id )'. Other wise, it must be something else in your code.
rawset it for use with metatables i think, it sets the variable without triggering the __index or __newindex metamethod