user: Question: in what playoffs the league was in the Semifinals
Columns: ['Year', 'League', 'Reg. Season', 'Playoffs', 'Owner(s)', 'Avg. Attendance']
Types: ['text', 'text', 'text', 'text', 'text', 'real']
Sample row: ['1990/91', 'NPSL', '3rd, American', 'Semifinals', 'N/A', 4031.0]
SQL:

assistant: SELECT "League" FROM "Table" WHERE "Playoffs" = 'Semifinals';