An apparatus includes a memory and processor. The memory stores a graphical representation of a first database that includes source tables and columns. The graphical representation includes nodes associated with source tables and columns. The processor receives an instruction to transfer data from the first database to columns of a second database specified by destination column names. The processor identifies a subset of source columns such that a similarity score for each is greater than a threshold. The similarity score indicates a degree of similarity between a specific destination column name and either the assigned source column name or a related term. The processor uses the subset to generate a pruned graphical representation that includes a subset of nodes. The processor uses this to generate executable code configured to copy data from the first database, determined from the pruned graphical representation, into the second database.