Database Join

Set join relationships on Stats button menu of table display window.   Joining does not require the same name for the Join field, or the same order for the records.

Pick the field in the database for the join. This must be a string/character or integer field. You will see the values in this field for the first records. 

Pick the table to join.

Pick the field in the join table database to use.  This must be a string/character or integer field.  You will see the values in this field for the first records.  Depending on the organization of records in the two databases, you might not see exact matches, but you should verify the general correspondence of the two fields.  If they have different lengths, you will not get any results.

Verify that the fields in the two tables have compatible records--they should have the same length and type of codings (string or integer; you cannot link on floats).  If the data starts with a "0", be particularly careful, as Excel can remove them and cause problems for things like Zip codes in New England and state FIPS for states starting with A and C.

You will see the number of records in the two databases. 

If there are records in the join table with duplicate values in the join field, you will be issued a warning.  This should not happen.  MICRODEM will allow you to use the first of the duplicates if you pick the allow multiple join matches, but you should insure that your data file is not corrupt, and that you understand why there are multiple records.

Select OK.

For US countries or states, you can link on either the name or the FIPS codes.  The name option must be used judiciously; a county might be coded as any of the following:

If the two databases do not use the same model for the names, the join will fail.  In contrast the FIPS code will have no ambiguity.  The FIPS code is also shorter and takes up less storage space, which may no longer be important, but was when a lot of the database functionality was developed.

 The MICRODEM default is now to strip the leading zeros from string fields (think FIPS and ZIPs) when used to join. If you want to use the files in another database with files that have not had this done, turn off the option on this form, or add them back in before using the databases elsewhere.

Example using joined fields.


Last revised  3/4/2017