CREATE FUNCTION aa(I INTEGER)
RETURNS INTEGER
LANGUAGE SQL
SPECIFIC aa
READS SQL DATA
BEGIN ATOMIC
CASE I
WHEN 0 THEN
RETURN 0;
WHEN 1 THEN
RETURN 1;
WHEN 2 THEN
RETURN 2;
WHEN 3 THEN
RETURN 3;
END CASE;
END
只是一个简单的case语句，就报错，但是如果是改成存储过程就成功，很是费解？请高手赐教，谢谢！
报错：
DB21034EThe command was processed as an SQL statement because it was not a
valid Command Line Processor command.During SQL processing it returned:
SQL0104NAn unexpected token "CASE WHEN" was found following "
".Expected tokens may include:"".LINE NUMBER=34.SQLSTATE=42601
但是，如果是这样就成功：
CREATE FUNCTION aa(I INTEGER)
RETURNS INTEGER
LANGUAGE SQL
SPECIFIC aa
READS SQL DATA
RETURN (
CASE I
