I'm not convinced of your analysis of your problem.
What stands out is that your command line is not balanced - the program-name has no opening quote.
Next issue is that the start
syntax will interpret such a line as a window-name followed by "...-sem1.db"
- and that is what it can't associate.
So - Easy solution is to add a pair of rabbits' ears around your desired window-name, and then another to balance the single enclosing the executable name.
start "your window name - may be empty" "%cd....
OR - since the executable-name does not contain spaces, remove the quote after .exe
start %cd....table.exe "%cd...sem1.db"
Either should cure your problem. Personally, I'd choose the first.