You can configure the DML command substitution at the transformation level or at the classifier level. By default, the classifier level configuration inherits the transformation level configuration. The default target command at the classifier level is set to <Inherit>. If the command at the classifier level is changed from <Inherit> to a different command, the classifier level configuration overrides the transformation level one.
Notes:
By default, all the source operations at the transformation level are mapped to <Default>.
For the source command Delete, the default target command is always Delete.
For the source command Update (or Modify on Enterprise Database Server), the default target command is Merge.
When the source command is Insert (or Create on Enterprise Database Server), then the default target command is Merge, if the target table has a unique key and mapped by multiple source classifiers in a transformation. If not, then the default target command is Insert.