Please give more details about age and health and type of dog.
Generally an adult dog (not an old one) can hold it in for several hours, which is not to say that is good for his kidneys.
If he is crated or confined in a small space he will hold it in. Even with the run of the house he will if he can, depending on the dog and his age. Larger dogs tend to be more willing than smaller breeds.
People who work and commute long hours should hire someone to walk the dog in the middle of the day (after and before you have walked him).
Please don't own a dog who is cooped up all day while you are gone.