CREATE TABLE table_4304 ("Year" FLOAT, "GDP at constant prices  ( THB trillions ) " CLOB, "GDP at constant prices growth rate  ( percent change ) " CLOB, "GDP at current prices  ( USD billions ) " CLOB, "Export volume of goods and services  ( percent change ) " CLOB, "Current account balance  ( percent of GDP ) " CLOB)

What is the GDP at constant prices for a current account balance of 12.8?
SELECT "GDP at constant prices (THB trillions)" FROM table_4304 WHERE "Current account balance (percent of GDP)" = '12.8'
SELECT "GDP at constant prices (THB trillions)" FROM "table_4304" WHERE "Current account balance (percent of GDP)" = '12.8'