To demonstrate some of the uses of the MERGE command in Epi Info's Analysis program, we have set up small databases for two separate clinics, A and B, and an independent laboratory , C , that provides services to A, B, and other clinics. Both clinics share data periodically by submitting files to an agency called Central, where they are merged into a central database.
Although the data items are imaginary and simplistic, the Demo has the following features:
A CLIENT View and a VISIT View for each clinic. In the data entry program, VISITs are linked to CLIENTs by the automatic Epi Info mechanism in which Fkey of a VISIT contains the UniqueKey of the CLIENT View to which it belongs.
A second set of keys based on CLIENT ID is also maintained to make things more explicit and for added safety. Both CLIENT and VISIT records contain ID fields, and the CLIENT's ID and Name are copied by Check Code into each new VISIT record.
Clinics A and B can MERGE results from Lab C into their own databases based on Visit Date and Lab Date. We have oversimplified in assuming that specimen dates and visit dates will match (they do). New results will correct or be appended to previous results. (MERGE with APPEND and UPDATE options)
Central can MERGE data from Clinics A and B into its own database, using Clinic name and CLIENT ID for CLIENT records and Clinic name, CLIENT ID, and VisitDate for VISIT records. Multi-variable keys are an important feature of MERGE.
The Fkey and UniqueKey relationship for the ENTER program is restored by another MERGE, this time a MERGE RELATE.
This model has relational databases at three levels (Lab—Clinic—Central), and each database has both parent and child records.
The examples are common to many structures in Public Health or Clinical Medicine, where data is received from more than one source at the periphery, and then merged with data from more than one agency or department to form a central database for analysis. Changes made at peripheral stations will update or be inserted into the central database.
FOLLOW THE NUMBERS: Essential steps in the Demo are numbered; the next is 2) SEE DATA AT LABORATORY C. Visit the other buttons later for a more complete experience.
Exit from the browser (X -button in the upper right corner) to go to the next step.