2014年9月12日 9:19:57 自动保存草稿

Dear sir or madam:
hello.I am a new postgressql user. And, now, I am studing psqlodbc.
There are some questions in my study.
Question 1: In file psqlodbc/test/Makefile, I don't find clean target. But we can use "make clean" to clean the obejct. And in my test makefile without target clean, i could't use "make clean". How is it work?
Question 2: We use "make installcheck" for complete regression test, and the test works well. But In file psqlodbc/test/Makefile, I only find "installcheck" and the work of creating .sql files. Now how is it work without some commands for pg_regress?
Question 3:What is their meaning and jobs, e.g REGRESS, EXTRA_CLEAN, REGRESS_OPTS?

Do I describ my question clearly, with my poor english?

Thanks a lot and look forward to hearing from you soon.
Best Regards.
Eric cai from beijing.