1. A method, comprising: selecting a source table comprising a plurality of rows and a target table resulting from a transformation applied to the rows of the source table; applying a first pre-processing method with respect to columns in the source and target tables to produce first category pre-processing output; using the first category pre-processing output to determine first category transformation rules with respect to at least one source table column and at least one target table column; applying a second pre-processing method to columns in the source and target tables to produce second category pre-processing output; and using the second category pre-processing output to determine second category transformation rules with respect to at least one source table column and at least one target table column.