Dachshunds are not stupid.  They are sometimes labeled as such because they don't learn as quickly as other breeds, or because they may occasionally ignore commands they have learned.  The key to getting a dachshund to learn or obey is motivation.  Dachshunds are not like border collies or shelties; they don't need you to give them a job.  They are quite content doing their own thing.  So, if you want a dachshund to do what you want, rather than what he/she wants, you need to motivate them.

 Motivation means you give your dachshund something he wants in return for him performing an action you want.  This is also called positive reinforcement.  Food treats are commonly used for this and can be very effective, but not all dachshunds are motivated by food.  For these dachshunds, it may be more effective to give them verbal praise, petting, or a quick round of tug of war (or some other game).  Experiment to find what your dog loves best to achieve the quickest results.

 Housetraining is best accomplished by never allowing bad habits to begin.  When you first bring your new dog home, whether he is a puppy or an older dog, consistency is key.  Dogs thrive on routine.  There are certain times your dog will need to go outside, so establish a routine of always taking him out at those times.  The times are upon waking in the morning or after a nap, after playing, and after eating.  Dogs which have not been previously trained to hold their bladders should not be expected to hold it very long.  A general rule of thumb for puppies is that they should be able to hold their bladder for as many hours as they are months old.  For older dogs, start them at about 4 hours maximum, and work up to longer times.  A crate is a wonderful tool for housetraining.  It uses the dog's natural desire to not soil where he sleeps to keep him from having an accident.  Again, though, don't keep him in there so long that he can't physically hold it.  This will be very upsetting to him and may destroy his desire to keep his kennel clean.

 When you take your dog outside, always use the same door.  After he goes outside, praise him verbally and excitedly, and give him a tasty treat.  Try to get him to go in the same area each time.  The scent from before will help prompt him to go.  If after a few minutes, he doesn't go, go back inside and put him immediately in his kennel.  Wait 30 minutes, then take him outside again.  Repeat this process until he has gone to the bathroom.  Only after he has gone should he be allowed any freedom to roam the house and play.  After a couple hours of freedom, put him back in the kennel for a couple hours.  If you follow this pattern conscientiously, your dog will learn his housetraining very quickly so that he earns more and more freedom.  However, don't be tempted to give him too much freedom too soon.  Also, don't stop giving him treats too soon for doing his business outside.  The treats can be tapered off, but this should be done gradually, and only after he has learned his housetraining very well.

 Accidents do happen, and no matter how vigilant you are or how smart your dog is, it's going to happen sooner or later.  If you catch your dog in the act, try to stop him immediately.  A loud "NO!" will usually stop him long enough for you to grab him and carry him quickly outside.  Other things to try are shaking a can of pennies or squirting him with water.  Under no circumstance should you ever rub his nose in his mess or spank him, especially if your dog is an adult when you get him.  If you adopted your dog from a shelter or rescue group, he may have fears stemming from past abuse or harsh treatment from his previous owners, and reacting negatively will only make him fear you.  If you don't catch your dog in the act and instead find the accident later, there is nothing you can do except be more vigilant in the future.  With some dogs, especially rescues, having an accident may even be an attention-getting device, like kids who act up in school to get their parent's attention.  For this reason, clean up accidents out of sight of the dog. 

 A special class of dog that requires more work on your part to housetrain is a former puppy mill dog.  These dogs typically have been kept in confined spaces their entire lives.  They have never known anything other than soiling their living area.  They will not keep a kennel clean, and in some cases, they may be so fearful of kennels that you can't use a kennel at all.  Some of them may eventually learn to be clean in a kennel but it may take months or years for that to happen.  With these dogs, praise and treats are the only answer.  Inside the house, it will probably be required that you provide an area for them that will keep them contained but allow them enough room to go without having to lie in it.  An exercise pen works well for this.  You'll have to try to his pattern of needing to go and then get him outside before it happens.  Oftentimes these dogs are several years old without ever having built up any ability to hold their bladders.  This ability will take some time to achieve.  The key is rewarding good behavior outside.  The dog will eventually learn that he gets something good for doing his thing outside, and start to hold it in anticipation of that.  If you are thinking of adopting a former puppy mill dog, you should go into it knowing full well what kind of housetraining problems may occur.  However, it is my belief that there is no dog that cannot be housetrained given enough time and patience.

 Finally, a few last notes on two problems which many think are a lack of housetraining, but aren't at all.  The first is submissive urination.  This is when a dog urinates when it gets excited, scared, or intimidated.  This is not a housetraining problem at all; in fact, the dog has no control over it.  Scolding or spanking will only make the problem worse and more difficult to get rid of.  If your dog has this tendency, here are some tips:

1. If your dog tinkles when you get home at night, try greeting your dog outside, or ignoring him when you first come in the door.

2. If your dog tinkles when meeting strangers, have the strangers ignore him until they have been there several minutes.

3. If your dog tinkles when you yell, don't yell!  If he tinkles at other times when frightened, such as during thunder storms, seek out the help of an animal behaviorist to help desensitize him to the things that scare him.

4. If you don't scold him when he tinkles and therefore make the problem worse, it will usually go away on its own as your dog gets older until it stops altogether.

The second problem is marking.  Marking can occur even with dogs that are well housetrained. 

Dogs mark to show dominance and claim territory.  Both males and females may mark.  Marking is closely tied with sexual maturity, which is why it is so beneficial to spay or neuter pets before they are sexually mature.  Dogs that are fixed early on usually won't ever develop marking behavior.  Even dogs that are fixed later in life will benefit, though.  After the sexual organs are removed, and therefore the hormones that go along with them, the urge to mark will usually lessen considerably or disappear altogether.