user: Question: What is the greatest CCBs with a Payload to GTO of –, and an Upper stage of SEC?
Columns: ['Version', 'Fairing', 'CCBs', 'SRBs', 'Upper stage', 'Payload to LEO', 'Payload to GTO', 'Launches to date']
Types: ['text', 'text', 'real', 'text', 'text', 'text', 'text', 'real']
Sample row: ['401', '4 m', 1.0, '–', 'SEC', '9,797kg', '4,750kg', 18.0]
SQL:

assistant: SELECT MAX("CCBs") FROM "Table" WHERE "Payload to GTO" = '–' AND "Upper stage" = 'SEC';