Excel spreadsheets can be stored as SQLite BLOB data.
DBBlobEditor can help you to store Excel spreadsheets as SQLite BLOB data:
Batch import excel files into SQLite BLOB
Batch export SQLite BLOB to EXCEL files
Convert your data online, free
Free in-browser converters for CSV, Excel, JSON, XML and SQL: Withdata Online Data Conversion. Large files, batch conversion or scheduling? See the offline desktop apps, or browse all data conversion tools.