Обсуждение: TRANSACTION error question

Hello All
Can anybody comment it ...
1. BEGIN work;
2. do something wrong (like 'drop table unknown_table');
3. do something right (like 'drop table exist_table');
receive error message .... (why?)

I using PQexec() and on (3) i receive PG_COMMAND_OK ! so how i can detect
error state ?