Table: territory_merges
Columns: former_country_name
former_codes
period_of_validity
iso_3166_3_code
new_country_names_and_codes

Question: Name the former codes for  merged into panama ( pa , pan , 591 )
SQL: SELECT "former_codes" FROM territory_merges WHERE "new_country_names_and_codes" = 'Merged into Panama ( PA , PAN , 591 )'

Question: Name the total number for period of validity for upper volta
SQL: SELECT COUNT("period_of_validity") FROM territory_merges WHERE "former_country_name" = 'Upper Volta'