You are perhaps attempting to enforce referential integrity, which you cannot do in this state. In case you were not told to do that, then don't and the message must go away.
For what it's worth, the assignment requisite appear bizzare. A PO table must be a header with PO number, make date, status. A PO line items table is where part numbers or their reference ID's should go.
The field in the table on the One-side of the relation should have a unique index. A duplicate index is not sufficient.
This is perhaps a gap in your understanding of relational database design. Please give us a enough description of the tables in question and their significant fields and data types.
In case you want to enforce referential integrity for a relationship, there should be a unique index (for example the primary key, however it can also be another index, as long as it is unique) on the field(s) on one side of the relationship. In case there is no such index, Access cannot enforce referential integrity.
I figure out the gap in my understanding of relational database design is explicit. It is plainly an area I am struggling with. In terms of the tables in in question, I have a table, "SampleDate" with 12 fields that I intend to join to 27 other tables named "element1", "element2", "element3" etc that comprise weather data.
The SampleDate table comprise the following fields:
- ID, which is autonumbered, and indexed as "Yes (No Duplicates)"
- Climate ID, which as explained prior is not a primary key, structured as "short text" data type and comprises alphanumeric data, and indexed as "Yes (Duplicates OK)". Climate ID's illustrate a weather station and may be periodic cause there are weather readings for each date (for example weather readings from each day of a month for one weather station)
- Date, which is not a primary key, and structured, structured as "Date/Time" data type and shown as long date, and indexed as "Yes (Duplicates OK)". Dates may be periodic as there can be readings from several weather stations on any given day.
- Weather parameter such as "Air Temp" (element 1), "Imply Wind Speed" (element 2), "entire Snowfall" (element 3)
What I am necessary to do is link my master list of dates "SampleDates" to each element and trace out the pertinent weather data as it relates to climate ID and date.
"No unique index found for the referenced field of the primary table"