user: Question: How many series numbers do the episodes originally aired on October 28, 1990?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: [81.0, 1.0, '"We\'ll Follow the Sun"', 'Gerry Cohen', 'Ron Leavitt & Michael G. Moye', 'September 23, 1990', '5.01']
SQL:

assistant: SELECT COUNT("No. in series") FROM "Table" WHERE "Original air date" = 'October 28, 1990';