Accessing logical columns using metadata table

Question

Hi,
I have a requirement to store data coming from multiple sources in various format into single table as the number of tables required is not determinable at development phase. Hence I have defined 2 tables,
1. Metadata table storing the information about logical columns in the incoming data.
2. Raw generic table where the actual data would be stored.
While accessible the logical data first I need to access the metadata table to fetch the column details and then access the raw table to provide actual data in those columns. Even though this option is available the code might not remain readable as need to use actual raw table column names in the code.
I have thought of view based access but again number of views required is not known at development time. Is there any option/feature available which would be able to provide logical view for the raw data?
thank you in advance.

Answer 1

Hi
Firstly, this sounds rather messy and is not something I would consider doing - but I shall give you the benefit of the doubt that all other options have been exhausted.
A way I can think of is that you could define your metadata a bit like the oracle data dictionary, then you could use something like APEX where you can use dynamic SQL to show a report on the data. Imagine something like this
DECLARE
l_sql VARCHAR2(32000);
BEGIN
l_sql : = 'SELECT ';
FOR i IN
(SELECT column_name
FROM my_table_data
WHERE table_name = :TARGET_TABLE)
LOOP
IF i = 1
THEN l_sql := l_sql||i.column_name;
ELSE l_sql := l_sql||', '||i.column_name;
END IF;
END LOOP;
l_sql := l_sql||' FROM '||:TARGET_TABLE;
RETURN l_sql;
END;Obviously you can make stick in predicates etc. if you need to but that would be a starting point?
Not very pretty though...
Cheers
Ben
http://www.munkyben.wordpress.com
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