Create sequence in Oracle without dropping it

Some of you might thinking how to create sequence for table which contains some records. You might always export all records from database, then eventually create sequence and after all import those records once again into database. Nevertheless there is a solution how to create this sequence using PL/SQL.

DECLARE
  seq_value_holder        NUMBER;
BEGIN
  -- create a sequence for YOUR_TABLE
  SELECT NVL(MAX(id), 0) + 1
  INTO seq_value_holder
  FROM YOUR_TABLE;
  EXECUTE immediate 'create sequence SEQ_YOUR_TABLE start with ' || seq_value_holder || ' increment by 1';
END;

Notes of Google recruitment process

A few days ago, I got an email with inquiry if I would like to participate in recruitment process to Google. I thought why not. It is always good to gain some experience around that. After a phone interview which was not successful for me, but I am not sad about that fact at all, I thought that I might give you some insight what areas you should refresh or just learn quickly. Of course your questions will be correlated with those areas which you picked up before phone interview, but I assume that some of them might be similar with those which I chose.

• Operating systems - monitors, semaphores, mutexes, linux, unix, processes, inode
• Algorithm Complexity - big O notation for different algorithms. Provide some complexity for sorting algorithms. Pick up those data structures which have following complexity for instance O(n log (n))
• Mathematics - calculate something very quickly in mind for instance 2 to the power of 32
• Trees - big O notation for different operation performed on trees like AVL, Binary trees
• Java - question related to programming language which you chose

Above list might looks like little chaotic, but I think that you might find some segment of knowledge which is required to get into to the next level of recruitment process in Google. Good luck!