Re: Looking for oracle/sql tutorials and advice

On Apr 27, 12:05 am, travel2light <everything2li..._at_yahoo.co.uk> wrote:
> Hi
>
> 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.
>
> Michael

1. 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?
2. 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.