user: Question: On which episode did actress Sela Ward make her last appearance?
Columns: ['Character', 'Portrayed by', 'First appearance', 'Last appearance', 'Duration', 'Episodes']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Mac Taylor CSI Detective', 'Gary Sinise', '"Blink" 1, 2, 3', '"Today is Life"', '1.01–9.17', '197']
SQL:

assistant: SELECT "Last appearance" FROM "Table" WHERE "Portrayed by" = 'Sela Ward';