user: Question: Tell me the competition for Half marathon
Columns: ['Year', 'Competition', 'Venue', 'Position', 'Notes']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [2006.0, 'World Junior Championships', 'Beijing , China', '2nd', '5000 m']
SQL:

assistant: SELECT "Competition" FROM "Table" WHERE "Notes" = 'Half marathon';