user: Question: What day did he play on Hard with Tom Mercer?
Columns: ['Date', 'Tournament', 'Surface', 'Partner', 'Opponents in the final', 'Score']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['March 3, 1992', 'Atlanta , U.S.', 'Clay', 'Dave Randall', 'Steve DeVries & David Macpherson', '3–6 3–6']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Surface" = 'Hard' AND "Partner" = 'Tom Mercer';