Oracle 11g 가상 열 가상 열 소개

Oracle 11G     Virtual Column



Oracle 11G          ，         ，      ，        ，         。



          ：



	column_name [datatype] [GENERATED ALWAYS] AS [expression] [VIRTUAL]



1.       select，update，delete   where   ，      DML  

2.           

3.           ，oracle        。

4.           



          ：



	CREATE TABLE EMPLOYEE

	(

		empl_id        NUMBER,

		empl_nm        VARCHAR2(50),

		monthly_sal    NUMBER(10,2),

		bonus          NUMBER(10,2),

		total_sal      NUMBER(10,2) GENERATED ALWAYS AS (monthly_sal*12 + bonus)

	);

	

 total_sal       

 

        ：



	SELECT column_name, data_type, data_length, data_default, virtual_column

	  FROM user_tab_cols

	 WHERE table_name = 'EMPLOYEE';

	 

	COLUMN_NAME | DATA_TYPE | DATA_LENGTH | DATA_DEFAULT             | VIRTUAL_COLUMN

	EMPL_ID     | NUMBER    | 22          | null                     | NO           

	EMPL_NM     | VARCHAR2  | 50          | null                     | NO           

	MONTHLY_SAL | NUMBER    | 22          | null                     | NO           

	BONUS       | NUMBER    | 22          | null                     | NO           

	TOTAL_SAL   | NUMBER    | 22          | "MONTHLY_SAL"*12+"BONUS" | YES        

	

virtual_column yes，      ，            VIRTUAL，        



	DROP TABLE EMPLOYEE PURGE;

	 

	CREATE OR REPLACE FUNCTION get_empl_total_sal ( p_monthly_sal   NUMBER,

													p_bonus         NUMBER)

	   RETURN NUMBER

	DETERMINISTIC

	IS

	BEGIN

	   RETURN p_monthly_sal * 12 + p_bonus;

	END;

	 

	CREATE TABLE EMPLOYEE

	(empl_id     NUMBER,

	 empl_nm     VARCHAR2(50),

	 monthly_sal NUMBER(10,2),

	 bonus       NUMBER(10,2),

	 total_sal   NUMBER(10,2) AS (get_empl_total_sal(monthly_sal, bonus)) VIRTUAL

	);

	

             



	CREATE INDEX idx_total_sal ON employee(total_sal);

	 

	SELECT index_name, index_type 

	  FROM user_indexes

	 WHERE table_name = 'EMPLOYEE';

	 

	INDEX_NAME     INDEX_TYPE                 

	IDX_TOTAL_SAL  FUNCTION-BASED NORMAL

	

           



	DROP FUNCTION get_empl_total_sal;

	 

	SELECT * FROM employee;

	*

	Error at line 0

	ORA-00904: "schema"."GET_EMPL_TOTAL_SAL": invalid identifier

	

         



	DROP TABLE EMPLOYEE PURGE;

	 

	CREATE TABLE EMPLOYEE

	(empl_id     NUMBER,

	 empl_nm     VARCHAR2(50),

	 monthly_sal NUMBER(10,2),

	 bonus       NUMBER(10,2)

	);

	 

	ALTER TABLE EMPLOYEE ADD (total_sal AS (monthly_sal * 12 + bonus));



            ，          。



	INSERT INTO employee (empl_id, empl_nm, monthly_sal, bonus)

	   WITH DATA AS

			(SELECT 100 empl_id, 'AAA' empl_nm, 20000 monthly_sal, 3000 bonus

			   FROM DUAL

			 UNION

			 SELECT 200, 'BBB', 12000, 2000

			   FROM DUAL

			 UNION

			 SELECT 300, 'CCC', 32100, 1000

			   FROM DUAL

			 UNION

			 SELECT 400, 'DDD', 24300, 5000

			   FROM DUAL

			 UNION

			 SELECT 500, 'EEE', 12300, 8000

			   FROM DUAL)

	   SELECT *

		 FROM DATA;

	 

	SELECT * FROM employee;

	 

	EMPL_ID | EMPL_NM | MONTHLY_SAL | BONUS | TOTAL_SAL

	100     | AAA     | 20000       | 3000  | 243000

	200     | BBB     | 12000       | 2000  | 146000

	300     | CCC     | 32100       | 1000  | 386200

	400     | DDD     | 24300       | 5000  | 296600

	500     | EEE     | 12300       | 8000  | 155600

	

       update       



	UPDATE employee

	   SET total_sal = 2000;

	 

	ORA-54017: UPDATE operation disallowed on virtual columns

	

               



	EXEC DBMS_STATS.GATHER_TABLE_STATS(user, 'EMPLOYEE');

	 

	SELECT column_name, num_distinct, 

		   display_raw (low_value, data_type)  low_value, 

		   display_raw (high_value, data_type) high_value

	  FROM dba_tab_cols

	 WHERE table_name = 'EMPLOYEE';

	 

	COLUMN_NAME | NUM_DISTINCT | LOW_VALUE | HIGH_VALUE

	TOTAL_SAL   | 5            | 146000    | 386200

	BONUS       | 5            | 1000      | 8000

	MONTHLY_SAL | 5            | 12000     | 32100

	EMPL_NM     | 5            | AAA       | EEE

	EMPL_ID     | 5            | 100       | 500

	

        



	DROP TABLE EMPLOYEE PURGE;

	 

	CREATE TABLE employee

	(empl_id     NUMBER,

	 empl_nm     VARCHAR2(50),

	 monthly_sal NUMBER(10,2),

	 bonus       NUMBER(10,2),

	 total_sal   NUMBER(10,2) AS (monthly_sal*12 + bonus)

	)

	PARTITION BY RANGE (total_sal)

		(PARTITION sal_200000 VALUES LESS THAN (200000),

		 PARTITION sal_400000 VALUES LESS THAN (400000),

		 PARTITION sal_600000 VALUES LESS THAN (600000),

		 PARTITION sal_800000 VALUES LESS THAN (800000),

		 PARTITION sal_default VALUES LESS THAN (MAXVALUE));

	 

	INSERT INTO employee (empl_id, empl_nm, monthly_sal, bonus)

	   WITH DATA AS

			(SELECT 100 empl_id, 'AAA' empl_nm, 20000 monthly_sal, 3000 bonus

			   FROM DUAL

			 UNION

			 SELECT 200, 'BBB', 12000, 2000

			   FROM DUAL

			 UNION

			 SELECT 300, 'CCC', 32100, 1000

			   FROM DUAL

			 UNION

			 SELECT 400, 'DDD', 24300, 5000

			   FROM DUAL

			 UNION

			 SELECT 500, 'EEE', 12300, 8000

			   FROM DUAL)

	   SELECT *

		 FROM DATA;

	 

	EXEC DBMS_STATS.GATHER_TABLE_STATS(user,'EMPLOYEE',granularity => 'PARTITION');

	 

	SELECT   table_name, partition_name, num_rows

		FROM user_tab_partitions

	   WHERE table_name = 'EMPLOYEE'

	ORDER BY partition_name;

	 

	TABLE_NAME | PARTITION_NAME | NUM_ROWS

	EMPLOYEE   | SAL_200000     | 2

	EMPLOYEE   | SAL_400000     | 3

	EMPLOYEE   | SAL_600000     | 0

	EMPLOYEE   | SAL_800000     | 0

	EMPLOYEE   | SAL_DEFAULT    | 0

	

      ，           



	UPDATE employee

	   SET monthly_sal = 30000

	 WHERE empl_id = 500;

	 

	ORA-14402: updating partition key column would cause a partition change

	

           ，     ENABLE ROW MOVEMENT



	ALTER TABLE employee ENABLE ROW MOVEMENT;

	 

	UPDATE employee

	   SET monthly_sal = 80000

	 WHERE empl_id = 500;

	 

	1 row updated.

	

                 



	CREATE TABLE employee_new

	(empl_id     NUMBER,

	 empl_nm     VARCHAR2(50),

	 monthly_sal NUMBER(10,2),

	 bonus       NUMBER(10,2),

	 total_sal   NUMBER(10,2) AS (get_empl_total_sal(monthly_sal, bonus))

	)

	PARTITION BY RANGE (total_sal)

		(PARTITION sal_200000 VALUES LESS THAN (200000),

		 PARTITION sal_400000 VALUES LESS THAN (400000),

		 PARTITION sal_600000 VALUES LESS THAN (600000),

		 PARTITION sal_800000 VALUES LESS THAN (800000),

		 PARTITION sal_default VALUES LESS THAN (MAXVALUE));

	 

	ORA-54021: Cannot use PL/SQL expressions in partitioning or subpartitioning columns