ArcPro Join Succeeds One Direction But Fails The Other

[ZachBodenner]

Hello,

I have a feature class and an Excel table with a matching field I want to join on. When I run the join from the feature class to the table, I get about 4/5 of the records matching. This seemed odd to me because I know the data matches up. I ran the join the other direction, from the Excel table to the feature class, and got a perfect number of joined records. 

This seems like a problem that might have an obvious solution, but what am I missing? Why would it be that a join would work one direction but not the other?

[DanPatterson]

convert the table to a table in a local geodatabase (Excel to Table

Excel To Table (Conversion)—ArcGIS Pro | Documentation

to ensure that you have removed that possible issue

Another possibility

Solved: Join working in one direction but not the other - Esri Community

[ZachBodenner]

Yes, that had occurred to me to. So I experimented, and the result was a join with more than the number of target records, with no warning of duplicate records. Upon inspection, there were definitely duplicate records (about 15 additional records). Also, I'm trying to reduce the amount of steps for a user to update a layer and it would be convenient to run it off an Excel sheet.

[DanPatterson]

well there is no way around duplicates and convenience vs accuracy/unexpected results is a tough call