Question

What would be the best way to insert XML data (that I get from a webpage) into PostgreSQL database?
I’m using Java and need a little help finding a good way to read this data into the database.

Answer 1

Postgres has (thanks to Daniel Lyons for pointing it out) native XML support which you can use to store your table. If you however want to shred your XML data manually, there are different possibilities to represent XML data in a database. The first question should be, if you want a very generic solution, that will be able to store any XML document or one that is specific to your domain (i.e. only allows XML documents of a certain structure). Depending on that, you will have a very flexible, universal representation which is however harder to query (the SQL needed will be quite complicated). If you have a more specific approach, the queries will be simpler, but you will need to create new tables or add new attributes to existing talbes every time you want to store another type of document or add a field to an existing document; so changing the schema will be harder (which is one major advantage of XML). This presentation should give you some ideas what are the different possibilities.

Also, you might consider to switch to some DB that supports Xquery, like DB2. The ability to natively query using XQuery, a language targeted at processing XML, will simplify things a lot.

UPDATE: Given your comment, your XML data (that you linked to) is perfectly relational. It can be mapped 1:1 to the following table:

CREATE TABLE mynt (
    ID          SERIAL     ,
    myntnafn    CHAR(3)    ,
    myntheiti   Varchar(255) ,
    kaupgengi   Decimal(15,2) ,
    midgengi    Decimal(15,2) ,
    solugengi   Decimal(15,2) ,
    dagsetning  TimeStamp      
)

So any mynt tag would be a record in the table and the corresponding sub-tags the attributes. The data types I gathered from your data, they might be wrong. The main problem is, IMO, that there is no natural primary key, so I added an autogenerated one.