Oracle中table函数的应用有哪些

2017-01-05 20:18:00来源:作者:人点击

Oracle中table函数的应用有哪些。表函数可接受查询语句或游标作为输入参数,并可输出多行数据。该函数可以平行执行,并可持续输出数据流,被称作管道式输出。应用表函数可将数据转换分阶段处理,并省去中间结果的存储和缓冲表。

1. 用游标传递数据

利用游标 REF CURSOR 可将数据集(多行记录)传递到PL/SQL函数:

SELECT *

FROM TABLE (myfunction (CURSOR (SELECT *

FROM mytab)));

2. 利用两个实体化视图(或表)作为样板数据

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. 定义对象类型和基于对象类型的表类型

定义对象类型并且为进一步引用做好准备。

(1)定义对象类型:TYPE sales_country_t

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;

(2)定义表类型:TYPE SUM_SALES_COUNTRY_T_TAB

CREATE TYPE sum_sales_country_t_tab AS TABLE OF sales_country_t;

(3)定义对象类型: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)定义表类型:TYPE SUM_SALES_GENDER_T_TAB

CREATE TYPE sum_sales_gender_t_tab AS TABLE OF sales_gender_t;

(5)定义对象类型:TYPE sales_roll_t

CREATE TYPE sales_roll_t AS OBJECT (

channel_desc VARCHAR2 (20),

country_id CHAR (2),

sum_amount_sold NUMBER

);

(6)定义表类型:TYPE SUM_SALES_ROLL_T_TAB

CREATE TYPE sum_sales_roll_t_tab AS TABLE OF sales_roll_t;

(7)检查一下建立的类型

SELECT object_name, object_type, status

FROM user_objects

WHERE object_type = 'TYPE';

4. 定义包:Create package and define REF CURSOR

CREATE OR REPLACE PACKAGE cursor_pkg

I 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. 定义表函数

(1)定义表函数: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)定义表函数: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)定义表函数: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)定义表函数: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. 调用表函数

下列 SQL 查询语句调用已被定义的表函数。

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')));

以上所述是小编给大家介绍的Oracle 中 table 函数的应用浅析,希望对大家有所帮助。

最新文章

123

最新摄影

微信扫一扫

第七城市微信公众平台