光標for循環中的PostgreSQL

Question

我們寫在PL/SQL（Oracle）的如下功能：

CREATE OR REPLACE PROCEDURE folder_cycle_check (folder_key IN NUMBER, new_parent_folder_key IN NUMBER) IS 
    parent_of_parent NUMBER; 
    ILLEGAL_CYCLE EXCEPTION; 
    CURSOR parent_c IS 
    SELECT parent_folder_key FROM folder 
     WHERE folder_key = new_parent_folder_key; 
BEGIN 

IF folder_key = new_parent_folder_key THEN 
    RAISE ILLEGAL_CYCLE; 
END IF; 

FOR parent_rec IN parent_c LOOP 
    BEGIN folder_cycle_check(folder_key, parent_rec.parent_folder_key); END; 
END LOOP; 

END; 

現在，我要改寫PL/pgSQL的（PostgreSQL的）相同的步驟來實現類似的功能。請幫助我併發送pl/pgsql函數。

編輯（從註釋格式的代碼）

CREATE OR REPLACE FUNCTION folder_cycle_check(IN folder_key INTEGER, IN new_parent_folder_key INTEGER) 
    RETURNS VOID 
AS $procedure$ 
    DECLARE parent_of_parent INTEGER; 
    PARENT_C CURSOR FOR 
     SELECT parent_folder_key 
     FROM folder 
     WHERE folder_key = new_parent_folder_key; 
BEGIN 
    IF folder_key = new_parent_folder_key THEN 
     RAISE EXCEPTION 'ILLEGAL_CYCLE'; 
    END IF 

    FOR parent_rec IN (SELECT parent_folder_key FROM folder WHERE folder_key = new_parent_folder_key) LOOP 
     PERFORM folder_cycle_check(folder_key,parent_rec.parent_folder_key); 
    END LOOP; 

    RETURN; 
END; 
$procedure$ 
LANGUAGE plpgsql;  

Answer 1

這應該工作：

CREATE OR REPLACE FUNCTION folder_cycle_check (p_folder_key INT4, p_new_parent_folder_key INT4) RETURNS VOID AS $$ 
DECLARE 
    v_parent_rec RECORD; 
BEGIN 
    IF folder_key = new_parent_folder_key THEN 
     RAISE EXCEPTION 'ILLEGAL_CYCLE'; 
    END IF; 
    FOR v_parent_rec IN SELECT parent_folder_key FROM folder WHERE folder_key = p_new_parent_folder_key LOOP 
     PERFORM folder_cycle_check(folder_key, v_parent_rec.parent_folder_key) 
    END LOOP; 
    RETURN; 
END; 
$$ LANGUAGE plpgsql;