user: Question: How many were first elected in California 7?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['California 7', 'George Miller', 'Democratic', 1974.0, 'Re-elected', 'George Miller (D) 68.3% Rick Tubbs (R) 31.7%']
SQL:

assistant: SELECT COUNT("First elected") FROM "Table" WHERE "District" = 'California 7';