Re: SQL - Creating a duplicate of an existing column

[CRPence <CRPbottle@xxxxxxxxx>]

  I recall using DESCRIBE against a prepared statement to describe 
its columns, so I am confident that a column of a table can be 
described from a prepared statement of:
    SELECT #{column_name} FROM #{table_name}

  There is a DESCRIBE TABLE statement, in addition to the more 
general DESCRIBE statement.  They would often be used _in_ a stored 
procedure, but I do not know about how either might be used to 
describe a stored procedure.

  There is also the SQL catalog VIEW SYSCOLUMNS, for which IIRC at 
least the ALLOCATE of a VARxxxx type is missing; the base table for 
that VIEW is QADBIFLD which is available to *ALLOBJ users, but any 
one of its logical files such as QADBILFI can be accessed instead by 
any user.  There is also the CL command DSPFFD to an output file. 
Finally there is the API QDBRTVFD for the format with the Qdb_Qddfmt 
Format Header and the fields with the Qdb_Qddffld Field Header to 
get the field information to without the output file or catalog 
approach.  I have not used QUSLFLD API, but that should give 
information on the database file fields as well.

Regards, Chuck

Pete Helgren wrote:
> Looking at the documentation, it looks like DESCRIBE is used
> for retrieving information about stored procedures, not
> tables or columns.
> At least all the examples seem to be using stored procedures.
>
> Carel Teijgeler wrote:
> > DESCRIBE may do the trick, I think you need the SQLDA for
> > that, but is according to me required in some aspects, as
> > you want ageneric solution..
> >
> > On 16-12-2009 at 14:34 Pete Helgren wrote:
> >
> > > I have a Java application that uses JDBC to the DB2 for i 
> > > database on my i. It is using a RENAME COLUMN function that
> > > isn't yet supported by DB2 (someday....). In any case, since
> > > I can't change the application I'd like to build a stored
> > > procedure to handle the function. I propose to do something
> > > like:
> > >
> > > "ALTER TABLE #{table_name} ADD COLUMN #{new_column_name}"
> > > "Update #{table_name} set #{new_column_name} = #{column_name}"
> > > "Alter table #{table_name} drop column #{column_name}"
> > >
> > > The kicker is, in order for this to be generic and work, I
> > > have to retrieve the attributes of the column I want to
> > > rename and copy and I don't know how to do that.  Does
> > > anybody have an SQL method for retrieving attributes of a
> > > column so that they can be used to create a column with the
> > > same attributes?