user: Question: What date was the 6d introduced?
Columns: ['English name', 'Irish name', 'Numeral', 'Reverse', 'Introduction', 'Withdrawal', '£1 Fraction']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Farthing', 'Feoirling', '¼d', 'Woodcock', '12 December 1928', '1 January 1962', '1/960']
SQL:

assistant: SELECT "Introduction" FROM "Table" WHERE "Numeral" = '6d';