Can I add salt to water to produce oxygen and hydrogen by electrolyzing water?

This is a typical electrolysis problem. The order of anion placement is: sulfide ion > iodide ion > bromide ion > chloride ion > hydroxide ion > sulfate ion > fluoride ion. Therefore, if you electrolyze pure water, OH discharges. the sequence should be after the chloride ions, so as you said, chlorine gas will be produced at the anode (correct one point, the electrode should become the anode during the electrolysis process)