The xo tool generates incorrect SQL for the Upsert function when targeting Oracle databases. The MERGE statement for the generated code does not include a space before the table alias (t), which results in invalid SQL.

Steps to Reproduce:

• Use xo to generate a schema/model file for an Oracle database.
• Inspect the Upsert function in the generated code.
• The MERGE statement is missing a space before the alias, resulting in:
  MERGE sales.orderst
  Instead of:
  MERGE sales.orders t

Proposed Solution:
Add a space before the table alias (t) in the generated MERGE statement.