CREATE TABLE table_204_15 (id NUMBER, "year" NUMBER, "date" CLOB, "venue" CLOB, "city" CLOB, "country" CLOB, "notes" CLOB)

how many times was a conference held in san francisco ?
SELECT COUNT(*) FROM table_204_15 WHERE "city" = 'san francisco'
SELECT COUNT(*) FROM "table_204_15" WHERE "city" = 'san francisco'