Splunk is really designed to index "events." Events are a record of something interesting that happened at a particular time. For the employee info data, I recommend that you use a lookup. Lookups are fast, and you don't need a sub-search, which will make your searches less complicated. You also don't need to mess with date ranges if you use lookups.
You will need to upload your employee info data to Splunk as a CSV file. You can update the file at will. (It's just a CSV in a particular directory on the Splunk server.)
Here is the best place to learn more, it is a tutorial on lookups: Use Field Lookups
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