Thanks Paige-   So I currently have a dataset with 1.5 million (+) entries belonging to around 700,000 individual patients.  Each entry consists of patient name, DOB, testing facility name, and test result.  Each day I get a couple hundred new entries sent in batches from every testing location. For example:   Current DataSet: Name: Master_List Facility     NAME                 DOB              Patient ID A              Smith, John         1/2/92            000123 A              Smith, John         1/2/92            000123 A              Person, Beth        2/2/95            000124 A              Patient, Abe          12/1/15         000125 A              Patient, Kelly         2/6/15          000126 B             Test, Person         12/12/18       000127 B             Another, Person    1/1/99          000128 B             Person, Beth          2/2/95          000124 C             Test, Person        12/12/18       000127   I need to merge in data from the following data sets (none of them have patient IDs)   DataSet 1 Facility        Name                      DOB A                Persons, Name      1/1/11 A                Another, Person       1/1/99 A                Athird, Person         1/1/11   DataSet 2 Facility       Name                 DOB B                Smith, John         1/2/92 B                Myname, IS        1/1/15 B                The, Other          1/1/15 B                 Person, Bee       1/15/15   and so one and so forth for 13 other facilities..     How would I merge these datasets together, assign new patient IDs to the patients who have no previous entries in my master list and also match assign the correct Patient IDs to the patients who do have previous entries?     ... View more