CREATE TABLE table_23280 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

How many were first elected in California 7?
SELECT "First elected" FROM table_23280 WHERE "District" = 'California 7'
SELECT "First elected" FROM "table_23280" WHERE "District" = 'California 7'