Re: Looking for oracle/sql tutorials and advice
Date: Sun, 27 Apr 2008 00:28:01 -0700 (PDT)
On Apr 27, 12:05 am, travel2light <everything2li..._at_yahoo.co.uk> wrote:
> I'm teaching myself oracle and I am looking for some easy to follow
> step by step tutorials on oracle and sql. I already found a few good
> introductions which cover the basics (and possibly more) but the ones
> I have found so far seem to leave a lot of questions. Two things I
> would like to learn how to do are:
> 1. How to 'unnormalise' so data. For example, I have followed a
> tutorial which shows how to normalise the contents of a column. So now
> the data has been put in a 'lookup' table and replaced with an ID
> (corresponding to the ID in the lookup table). How do I get the data
> back into the table it originally came from?
> 2. Working with foreign keys. So far my studied have given me the
> impression that this is the key to how relational databases work -
> what makes them powerful/useful etc. But the only way I have seen to
> access this power is by creating queries, to make a report. But what
> about when one wants to add new data? e.g. in the Human Resources
> example (which comes with Oracle 10g Express) there is a table for
> employees, and also for departments. The department_id column on the
> employees table is constrained to the department_id column in the
> departments table. Now I want to create an application that displays
> the employees table, and also can display a form for adding new
> employees. On this form I would like there to be a button, next to
> each employee, which brings up the list of departments. From this I
> can select the department from this list. Is it possible to do
> something like this?
> Thanks for any advice.
- I'm not sure if you want to reorganise your schema design, move data between tables (insert ... select) or restore to a point in time (select ... as of timestamp ..., or flashback table/database though I don't think XE provides that). Did you delete the original data?
- I'm not sure this has much to do with foreign keys. It sounds like an Application Express question about how to define a button that pops up a selection list populated from a query. I'm sure there there's a way but I'm afraid I don't know Apex.