fix SQL errors

Author: ksmin23

utils/gen_fake_mysql_data.py

@@ -30,7 +30,7 @@
 ) ENGINE=InnoDB AUTO_INCREMENT=0;
 '''
 
-DROP_TABLE_SQL_FMT = '''DROP TABLE IF NOT EXISTS {database}.{table};'''
+DROP_TABLE_SQL_FMT = '''DROP TABLE IF EXISTS {database}.{table};'''
 
 INSERT_SQL_FMT = '''INSERT INTO {database}.{table} (customer_id, event, sku, amount, device, trans_datetime) VALUES("{customer_id}", "{event}", "{sku}", {amount}, "{device}", "{trans_datetime}");'''