user: Question: How many digital terrestrial channels are there for Channel 4?
Columns: ['Position', 'Channel', 'Analogue terrestrial channel', 'Digital terrestrial channel', 'Internet']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'BBC One', '1', '1 50 (HD)', 'bbc.co.uk']
SQL:

assistant: SELECT COUNT("Digital terrestrial channel") FROM "Table" WHERE "Channel" = 'Channel 4';