Verify value exist in table...

[jovery]

You've not said which version so I've assumed 9i in which the following will work.

SELECT *
FROM table
WHERE (SELECT condition_column FROM condition_table) = condition_to_proceed

eg.

If you have a STATE table with a column TEST and you want to make sure TEST = 1 to proceed your statement would look like 

SELECT *
FROM any_table
WHERE (SELECT test FROM state) = 1;

Hope that helps