IF 语句而不是 select

Question

Informix 它可以工作，如何在 Oracle 中这样做？

IF (uzel NOT IN (SELECT a.uzel FROM user_setup.menu a WHERE a.vetka <> a.uzel
                             AND a.vetka IN (SELECT vetka FROM user_setup.param_menu)))
          THEN
             --;
          END IF;

Answer 1

在 Oracle 中，您需要使用不同的方法：

DECLARE
   usel1 <specify here the data type for the usel>;
BEGIN

  SELECT a.uzel INTO usel1 
  FROM user_setup.menu a 
  WHERE a.vetka <> a.uzel AND a.usel = uzel
   AND a.vetka IN (SELECT vetka FROM user_setup.param_menu))

   -- this means the record is found.

EXCEPTION
   WHEN NO_DATA_FOUND THEN
     -- do other processing here
END;

Answer 2

试试这个：

DECLARE
  temp NUMBER;
  v_uzel user_setup.menu.uzel%TYPE;
BEGIN    
  SELECT COUNT(*) 
  INTO temp
  FROM dual
  WHERE EXISTS (SELECT A.uzel 
                FROM user_setup.menu A 
                WHERE A.vetka <> A.uzel
                AND A.uzel = v_uzel
                AND A.vetka IN (SELECT vetka FROM user_setup.param_menu));


  IF temp < 1 THEN
    -- code here 

  END IF;
END;