Much like the federal government, which has enacted the Uniformed Services Employment and Reemployment Rights Act (USERRA), many states have enacted laws to protect the employment status of the men and women who serve in the armed forces (38 USC 4301et seq.).
Oregon has enacted such a law.
Remember that USERRA, a federal law, preempts any state law that is less protective of the employment and reemployment rights of uniformed service people. That is, if Oregon law is less protective than USERRA, the rights given by USERRA will apply. Likewise, if Oregon law is more protective than USERRA, the Oregon law will apply.
There is additional information.