Progress Open Edge Union I am attempting to union together 2 queries in progress DB
Unfortunately, this is returning me a syntax error.
Are union queries unsupported in progress DB?
     SELECT 0, 'All'
     UNION ALL
     SELECT custcode, custname
     FROM pub.pv_customer
That may depend on what version of OpenEdge you are querying. Reasonably modern releases do support UNION:
https://www.progress.com/docs/default-source/openedge/progress-openedge-sql-compliance-to-core-sql-2011.pdf?sfvrsn=0
(this applies to OpenEdge 11.5 and above)