I downloaded the entire World Bank data. Now I have almost 900 Excel files, each of which has almost 1 million rows. The columns of these Excel files are years, which are approximately from 1960 to 2023. I wanted to save all these Excel files in a database like Postgres, but I don’t know how to add another Excel file to it after importing an Excel file.

I tried to import the first excel file. The names of the columns of these files are the names of the countries, the names of the series, and the years, respectively. In some of the cells where there is no information, he used “..” Because of this, when I consider the data type of the year column to be an integer, it gives an error. I wanted to know how to create a database with 10 million rows with all the Excel files that I have so that later I can use them using Python codes to find similarities between time series data?