user: Question: What release date has 6998 as the production num.?
Columns: ['Title', 'Series', 'Director', 'Production Num.', 'Release date']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Mr. and Mrs. Is the Name', 'MM', 'Friz Freleng', '6611', '1935-01-19']
SQL:

assistant: SELECT "Release date" FROM "Table" WHERE "Production Num." = '6998';