Q: When is a DECLARE statement needed?

[類別] PL/SQL
[問題] 什麼時候需用到DECLARE語法?

Answer:
DECLARE是用在PL/SQL區塊(block)內。一個PL/SQL block被DECLARE, BEGIN, EXCEPTION, END四個關鍵字分成三個部份:

DECLARE

  -- Declarative part(optional)

  -- for declartions of local types, variables, subprograms

BEGIN

  -- Executable part(required)

  -- statements

  EXCEPTION

    -- Exception-handling part(optional)

END;

所以，當你有需要宣告變數等，就會把它放在DECLARE的區塊內。