Database Query with no key values

Marley777 · Post by **Marley777** » Mon Oct 24, 2005 8:57 am

I am trying to combine input from a transformer stage along with a max id value from a db2 table in datastage. The information in the two inputs is not related to do a lookup on a key value. Has anyone ever done this?

kcbland · Post by **kcbland** » Mon Oct 24, 2005 9:03 am

Use a pseudo column with a literal value as the key in your select max query. Now do the lookup using the literal value.

Marley777 · Post by **Marley777** » Mon Oct 24, 2005 9:27 am

What do you mean by pseudo column?

kcbland · Post by **kcbland** » Mon Oct 24, 2005 9:32 am

A pseudo column:

Code: Select all

select 'I am not a real column' "NOT_REAL_COLUMN", max(primary_key) "MAX_KEY" from your_table"

will return two columns of data: NOT_REAL_COLUMN and MAX_KEY in your result set.

A pseudo column is a literally defined column that doesn't exist in the underlying data. You supply an alias to give it a name. A very elementary SQL technique.