Re: SQL - Creating a duplicate of an existing column

[Pete Helgren <Pete@xxxxxxxxxx>]

"Look a little further. Then next section in the DB2 SQL Reference 
covers DESCRIBE TABLE."

Yes it does.  I had a copy of the SQL Reference for Cross Platform 
Development manual open when I did my search and that is why I missed 
it.  Meanwhile I came up with this hacky workaround but now I'll go back 
and revisit the DESCRIBE TABLE function.

Pseudo Code: (Hacky workaround)

# Clone the existing table adding the aliased column
     execute "create table tmp_rename as (select 
#{table_name}.*,#{table_name}.#{column_name} as #{new_column_name} from 
#{table_name}) definition only"                                      
# Drop the old column
     execute "Alter table tmp_rename drop column #{column_name}"
# Rename the current table
     execute "RENAME table #{table_name} to tmp_oldtbl"
# Rename the new table back to old
    execute "RENAME table tmp_rename to #{table_name}"
# Drop the old table
    execute "Drop table tmp_oldtbl"

The copy of the table and dropping of columns and tables and rename of 
tables is probably very inefficient so I will take a look at the 
describe function.  Of course I need to copy the data from the old to 
new table in these steps as well

Thanks.

Pete



Simon Coulter wrote:
> On 17/12/2009, at 9:39 AM, 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.
> >     
>
> Look a little further. Then next section in the DB2 SQL Reference  
> covers DESCRIBE TABLE.
>
> Regards,
> Simon Coulter.
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