How do you implement a query that examines if a line is connected at both ends?

Hey all,
I want to write a query that examines if a line is connected at both ends (a very common rule in the area of topology) but I cannot seem to find an easy way to do so. (By connected I mean that there is another line that 'touches' the given line.)
The problem I have is that I cannot find any way to retrieve the start or end point of a line geometry. (I am using Oracle 8.1.7.)
If someone can give me any suggestions I would be very grateful.
Thanks in advance,
Johan Behrenfeldt

Hey,
Thanks for both of the answers.
I eventually solved the problem using Java stored procedures. However, in the case that someone is looking for the answer to the same question I was asking I just wanted to point out a few things.
Jens' solution seems correct and it was my first approach as well. However, there is a case when it fails and that is if the lines connect in the shape of a triangle. You would find a line that has connected lines at both ends but the connected lines would have a non-empty intersection and would therefore be discarded incorrectly.
The second suggested solution works, but I have found it less than trivial to find the ordinate tuple that contains the start point of the line string. Many GIS applications insists on using the ordinate array as a storage place for data. They will use the sdo_etype 0 to hide the information from Spatial, but when manipulating the geometries manually they cause a great deal of trouble. (Try writing an sql query to retrieve the start point of a line.)
The latter is, however, what I ended up using in the end. With the help of Java stored procedures the task became fairly easy.
Thank you, in any case, for all your help, and I apologize if I come off as a smart-allick here. ;-)
Johan Behrenfeldt

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