Changes a merge into query to an merge top into query.

top clause is only supported by some dialects like MS SQL Server.

Examples

Affect 5 matched rows at most:

await db.mergeInto('person')
  .top(5)
  .using('pet', 'person.id', 'pet.owner_id')
  .whenMatched()
  .thenDelete()
  .execute()

The generated SQL (MS SQL Server):

merge top(5) into "person"
using "pet" on "person"."id" = "pet"."owner_id"
when matched then
  delete

Affect 50% of matched rows:

await db.mergeInto('person')
  .top(50, 'percent')
  .using('pet', 'person.id', 'pet.owner_id')
  .whenMatched()
  .thenDelete()
  .execute()

The generated SQL (MS SQL Server):

merge top(50) percent into "person"
using "pet" on "person"."id" = "pet"."owner_id"
when matched then
  delete