user: Question: What is the production code of the episode directed by David Solomon? 
Columns: ['No. in series', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (millions)']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '" Pilot "', 'Jace Alexander', 'Matt Nix', 'June28,2007', 'BN100', '4.0']
SQL:

assistant: SELECT "Production code" FROM "Table" WHERE "Directed by" = 'David Solomon';