I'm trying to join an excel file to ArcMap. The information in the excel file is clean and doesn't contain any characters that might hinder the joining process. However, when I join the file, all of the information in the attribute table comes up as "null", and the information in the top row of the attribute table is the first county in the first cell of my excel file. I was wondering if there was a way to fix this.
Save your excel file as a .csv, or export the excel file as a .dbase table or into a geodatabase. You should then be able to successfully join.
Might be good idea to review this since you said it is clean and doesn't contain any characters, sometimes you might be missing something...
Sometimes I have needed to be dynamically linked to an Excel sheet that others interact with. One thing you might try is to open Access, go to the External Data tab, hit the Excel button, select Link to the data source by creating a linked table, and ensure your fields are all importing as the correct type. If you create a database connection with the Access table from ArcMap you can have the data displayed and see live edits of the spreadsheet (maybe you need to hit refresh). If I remember correctly the weird part was that the changes in ArcMap happened before I hit save in Excel.