TABLE函數可接受查詢語句或游標作為輸入參數，并可輸出多行數據。該函數可以平行執行，并可持續輸出數據流，被稱作管道式輸出。應用TABLE函數可將數據轉換分階段處理，并省去中間結果的存儲和緩沖表.
TABLE函數（它是9i中的新特性），實際上是將一個存儲在內存中的對象（以流的方式存儲的）結構化以后，使這個對象能以表的方式查詢。他對流對象的結構化轉換就決定的它的效率大大遜于對普通表和臨時表的查詢效率.
TABLE函數可接受查詢語句或游標作為輸入參數，并可輸出多行數據。該函數可以平行執行，并可持續輸出數據流，被稱
1. 用游標傳遞數據
利用游標 REF CURSOR 可將數據集（多行記錄）傳遞到PL/SQL函數:
1
SELECT *
2 FROM TABLE (myfunction (CURSOR (SELECT *
3 FROM mytab)));
2.利用兩個實體化視圖（或表）作為樣板數據
CREATE MATERIALIZED VIEW sum_sales_country_mv
BUILD IMMEDIATE
REFRESH COMPLETE
ENABLE QUERY REWRITE
AS
SELECT SUBSTR (s.calendar_month_desc, 1, 4) YEAR, c.country_id country,
SUM (sum_amount_sold) sum_amount_sold
FROM sum_sales_month_mv s, customers c
WHERE s.cust_id = c.cust_id
AND c.country_id IN ('US', 'UK', 'FR', 'ES', 'JP', 'AU')
GROUP BY SUBSTR (s.calendar_month_desc, 1, 4), c.country_id;
CREATE MATERIALIZED VIEW sum_es_gend_mv
BUILD DEFERRED
REFRESH FAST
ENABLE QUERY REWRITE
AS
SELECT SUBSTR (s.calendar_month_desc, 1, 4) YEAR,
s.calendar_month_desc cal_month, c.cust_gender,
SUM (sum_amount_sold) sum_amount_sold
FROM sum_sales_month_mv s, customer c
WHERE s.cust_id = c.cust_id
AND c.country_id = 'ES'
AND sunstr (s.calendar_month_desc, 1, 4) = '2000'
GROUP BY SUBSTR (s.calendar_month_desc, 1, 4),
s.calendar_month_desc,
c.cust_gender;
3.定義對象類型和基于對象類型的表類型
定義對象類型并且為進一步引用做好準備
（1）定義對象類型：
CREATE TYPE sales_country_t AS OBJECT (
YEAR VARCHAR2 (4),
country CHAR (2),
sum_amount_sold NUMBER
);
（2）定義表類型：TYPE SUM_SALES_COUNTRY_T_TAB
CREATE TYPE sum_sales_country_t_tab AS TABLE OF sales_country_t;
（3）定義對象類型：TYPE sales_gender_t
CREATE TYPE sales_gender_t AS OBJECT (
YEAR VARCHAR2 (4),
country_id CHAR (2),
cust_gender CHAR (1),
sum_amount_sold NUMBER
);
（4）定義表類型：TYPE SUM_SALES_GENDER_T_TAB
CREATE TYPE sum_sales_gender_t_tab AS TABLE OF sales_gender_t;
（5）定義對象類型：TYPE sales_roll_t
CREATE TYPE sales_roll_t AS OBJECT (
channel_desc VARCHAR2 (20),
country_id CHAR (2),
sum_amount_sold NUMBER
);
（6）定義表類型：TYPE SUM_SALES_ROLL_T_TAB
CREATE TYPE sum_sales_roll_t_tab AS TABLE OF sales_roll_t;
（7）檢查一下建立的類型：
SELECT object_name, object_type, status
FROM user_objects
WHERE object_type = 'TYPE';
4.定義包：
Create package and define REF CURSOR
CREATE OR REPLACE PACKAGE cursor_pkg
IS
TYPE sales_country_t_rec IS RECORD (
YEAR VARCHAR (4),
country CHAR (2),
sum_amount_sold NUMBER
);
TYPE sales_gender_t_rec IS RECORD (
YEAR VARCHAR2 (4),
country_id CHAR (2),
cust_gender CHAR (1),
sum_amount_sold NUMBER
);
TYPE sales_roll_t_rec IS RECORD (
channel_desc VARCHAR2 (20),
country_id CHAR (2),
sum_amount_sold NUMBER
);
TYPE sales_country_t_rectab IS TABLE OF sales_country_t_rec;
TYPE sales_roll_t_rectab IS TABLE OF sales_roll_t_rec;
TYPE strong_refcur_t IS REF CURSOR
RETURN sales_country_t_rec;
TYPE row_refcur_t IS REF CURSOR
RETURN sum_sales_country_mv%ROWTYPE;
TYPE roll_refcur_t IS REF CURSOR
RETURN sales_roll_t_rec;
TYPE refcur_t IS REF CURSOR;
END corsor_pkg;
5. 定義表函數
（1）定義表函數：FUNCTION Table_Ref_Cur_Week
CREATE OR REPLACE FUNCTION table_ref_cur_week (cur CURSOR.refcur_t)
RETURN sum_sales_country_t_tab
IS
YEAR VARCHAR (4);
country CHAR (2);
sum_amount_sold NUMBER;
objset sum_sales_country_t_tab := sum_sales_country_t_tab ();
i NUMBER := 0;
BEGIN
LOOP
-- Fetch from cursor variable
FETCH cur
INTO YEAR, country, sum_amount_sold;
EXIT WHEN cur%NOTFOUND;
-- exit when last row is fetched
-- append to collection
i := i + 1;
objset.EXTEND;
objset (i) := sales_country_t (YEAR, country, sum_amount_sold);
END LOOP;
CLOSE cur;
RETURN objset;
END;
（2）定義表函數：FUNCTION Table_Ref_Cur_Strong
CREATE OR REPLACE FUNCTION table_ref_cur_strong (cur cursor_pkg.strong_refcur_t)
RETURN sum_sales_country_t_tab PIPELINED
IS
YEAR VARCHAR (4);
country CHAR (2);
sum_amount_sold NUMBER;
i NUMBER := 0;
BEGIN
LOOP
FETCH cur
INTO YEAR, country, sum_amount_sold;
EXIT WHEN cur%NOTFOUND; -- exit when last row fetched
PIPE ROW (sales_country_t (YEAR, country, sum_amount_sold));
END LOOP;
CLOSE cur;
RETURN;
END;
（3）定義表函數：FUNCTION Table_Ref_Cur_row
CREATE OR REPLACE FUNCTION table_ref_cur_row (cur cursor_pkg.row_refcur_t)
RETURN sum_sales_country_t_tab PIPELINED
IS
in_rec cur%ROWTYPE;
out_rec sales_country_t := sales_country_t (NULL, NULL, NULL);
BEGIN
LOOP
FETCH cur
INTO in_rec;
EXIT WHEN cur%NOTFOUND; -- exit when last row is fetched
out_rec.YEAR := in_rec.YEAR;
out_rec.country := in_rec.country;
out_rec.sum_amount_sold := in_rec.sum_amount_sold;
PIPE ROW (out_rec);
END LOOP;
CLOSE cur;
RETURN;
END;
（4）定義表函數：FUNCTION Gender_Table_Ref_Cur_Week
CREATE OR REPLACE FUNCTION gender_table_ref_cur_week (cur cursor_pkg.refcur_t)
RETURN sum_sales_gender_t_tab
IS
YEAR VARCHAR2 (4);
country_id CHAR (2);
cust_gender CHAR (1);
sum_amount_sold NUMBER;
objset sum_sales_gender_t_tab := sum_sales_gender_t_tab ();
i NUMBER := 0;
BEGIN
LOOP
FETCH cur
INTO YEAR, country_id, cust_gender, sum_amount_sold;
EXIT WHEN cur%NOTFOUND; -- exit when last row is fetched
i := i + 1;
objset.EXTEND;
objset (i) :=
sum_sales_gender_t (YEAR, country_id, cust_gender, sum_amount_sold);
END LOOP;
CLOSE cur;
RETURN objset;
END;
6. 調用表函數
下列 SQL 查詢語句調用已被定義的表函數。
SELECT *
FROM TABLE (table_ref_cur_week (CURSOR (SELECT *
FROM sum_sales_country_mv)));
SELECT *
FROM TABLE (table_ref_cur_strong (CURSOR (SELECT *
FROM sum_sales_country_mv)));
SELECT *
FROM TABLE (table_ref_cur_row (CURSOR (SELECT *
FROM sum_sales_country_mv)));
SELECT *
FROM TABLE (table_ref_cur_week (CURSOR (SELECT *
FROM sum_sales_country_mv
WHERE country = 'AU')));
posted on 2010-12-19 22:53
xrzp 閱讀(1687)
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