Who wrote the episodes directed by David Straiton?
CREATE TABLE table_21312845_1 (written_by VARCHAR, directed_by VARCHAR)
SELECT written_by FROM table_21312845_1 WHERE directed_by = "David Straiton"
### Context: CREATE TABLE table_21312845_1 (written_by VARCHAR, directed_by VARCHAR) ### Question: Who wrote the episodes directed by David Straiton? ### Answer: SELECT written_by FROM table_21312845_1 WHERE directed_by = "David Straiton"