user: Question: If the original air date is April 1, 2003, what number in the series is this episode?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date']
Types: ['real', 'real', 'text', 'text', 'text', 'text']
Sample row: [159.0, 1.0, '"Critical Condition (Part 3)"', 'Jeannot Szwarc', 'Charles Holland', 'September 24, 2002']
SQL:

assistant: SELECT "No. in series" FROM "Table" WHERE "Original air date" = 'April 1, 2003';