在将数据从Excel导出到POSTGRESQL时，值NA被转换为NULL。它应该以NA的形式存在。我使用python进行以下代码的传输。

try:
    df = pd.read_excel(r"D:\Projects\MLT\File.xlsx")
    # print(df.head(10))
    print(df.shape[0])
except Exception as error:
    print(error,'Unable to Read the Data')

# Create Alchemy Engine to write the data of dataframe on table
try:
    engine   = create_engine('params')
    df.to_sql('table',engine,if_exists='append',schema='schema_name', index=False)
except Exception as error:
    print(error,'Unable to Insert the Data')