CREATE TABLE table_67942 ("Country" CLOB, "Player name" CLOB, "Period" CLOB, "Position" CLOB, "Matches" CLOB, "Goals" CLOB)

Name the period with matches of 0 0 of portugal
SELECT "Period" FROM table_67942 WHERE "Matches" = '0 0' AND "Country" = 'portugal'
SELECT "Period" FROM "table_67942" WHERE "Country" = 'portugal' AND "Matches" = '0 0'