how many people wrote the episode directed by rob schrab?
CREATE TABLE table_28081876_4 (written_by VARCHAR, directed_by VARCHAR)
SELECT COUNT(written_by) FROM table_28081876_4 WHERE directed_by = "Rob Schrab"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_28081876_4 (written_by VARCHAR, directed_by VARCHAR) Question: how many people wrote the episode directed by rob schrab? [/INST] SELECT COUNT(written_by) FROM table_28081876_4 WHERE directed_by = "Rob Schrab" </s>