A Broken chair is very common because they take more punishment than any other piece of furniture! Over time, the glue become void of moisture and the joints pull apart. An important tip is to nip the problem in the bud and make repairs before the joints become really loose!
A small drill, a small finish nail, a hammer and a nail set is all you need for this project. Underneath the dowel, no one can see the nail hole. Remember, to get the leg apart, clean out the old glue from hole and dowel and re-glue before you drill and nail. Also, when getting it all back together, use your hands or a rubber mallet to hit together. Do not use a regular hammer because it will damage the wood!