Inlist的绑定优化（书摘备查）

-- 建立类型
CREATE OR REPLACE TYPE numtabletype AS TABLE OF NUMBER;

CREATE OR REPLACE TYPE vartabletype AS TABLE OF VARCHAR2 (1000);

-- 解析字符串
CREATE OR REPLACE FUNCTION str2numlist (p_string IN VARCHAR2)
RETURN numtabletype
AS
v_str LONG DEFAULT p_string || ',';
v_n NUMBER;
v_data numtabletype := numtabletype ();
BEGIN
LOOP
v_n := TO_NUMBER (INSTR (v_str, ','));
EXIT WHEN (NVL (v_n, 0) = 0);
v_data.EXTEND;
v_data (v_data.COUNT) := LTRIM (RTRIM (SUBSTR (v_str, 1, v_n - 1)));
v_str := SUBSTR (v_str, v_n + 1);
END LOOP;

RETURN v_data;
END;

CREATE OR REPLACE FUNCTION str2varlist (p_string IN VARCHAR2)
RETURN vartabletype
AS
v_str LONG DEFAULT p_string || ',';
v_n VARCHAR2 (2000);
v_data vartabletype := vartabletype ();
BEGIN
LOOP
v_n := INSTR (v_str, ',');
EXIT WHEN (NVL (v_n, 0) = 0);
v_data.EXTEND;
v_data (v_data.COUNT) := LTRIM (RTRIM (SUBSTR (v_str, 1, v_n - 1)));
v_str := SUBSTR (v_str, v_n + 1);
END LOOP;

RETURN v_data;
END;

-- 绑定查询
SELECT /*+ ordered use_nl(a,u) */
ID, NAME, nick
FROM TABLE (str2numlist (:bind0)) a, users u
WHERE u.ID = a.COLUMN_VALUE;

SELECT /*+ leading(a) */
ID, NAME, nick
FROM users u
WHERE ID IN (SELECT *
FROM TABLE (str2numlist (:bind0)) a);

SELECT /*+ index(u ind_users_id) */
ID, NAME, nick
FROM users u
WHERE ID IN (SELECT *
FROM THE (SELECT CAST (str2numlist (:bind0) AS numtabletype)
FROM DUAL)
WHERE ROWNUM < 1000);