Oracle PL/SQL Tutorial/Object Oriented/CAST
Содержание
- 1 Cast value to custom type
- 2 The CAST Function
- 3 The CAST function converts an object type (such as a VARRAY) into a common type that can be queried. Oracle 10g automatically converts the VARRAY without the CAST.
- 4 Transform a collection into a table and reference it in a SQL query.
- 5 Use view to cast records in result set to a type
Cast value to custom type
SQL>
SQL> CREATE TABLE DEPT (DEPTNO NUMBER(2),DNAME VARCHAR2(14),LOC VARCHAR2(13) );
Table created.
SQL>
SQL> INSERT INTO DEPT VALUES (10, "ACCOUNTING", "NEW YORK");
1 row created.
SQL> INSERT INTO DEPT VALUES (20, "RESEARCH", "DALLAS");
1 row created.
SQL> INSERT INTO DEPT VALUES (30, "SALES", "CHICAGO");
1 row created.
SQL> INSERT INTO DEPT VALUES (40, "OPERATIONS", "BOSTON");
1 row created.
SQL>
SQL>
SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
2 ENAME VARCHAR2(10),
3 JOB VARCHAR2(9),
4 MGR NUMBER(4),
5 HIREDATE DATE,
6 SAL NUMBER(7, 2),
7 COMM NUMBER(7, 2),
8 DEPTNO NUMBER(2));
Table created.
SQL>
SQL> INSERT INTO EMP VALUES (7369, "SMITH", "CLERK", 7902, TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7499, "ALLEN", "SALESMAN", 7698, TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7521, "WARD", "SALESMAN", 7698, TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7566, "JONES", "MANAGER", 7839, TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10);
1 row created.
SQL>
SQL> create or replace type emp_type
2 as object
3 (empno number(4),
4 ename varchar2(10),
5 job varchar2(9),
6 mgr number(4),
7 hiredate date,
8 sal number(7, 2),
9 comm number(7, 2)
10 );
11 /
Type created.
SQL>
SQL> create or replace type emp_tab_type
2 as table of emp_type
3 /
Type created.
SQL> create table dept_and_emp
2 (deptno number(2) primary key,
3 dname varchar2(14),
4 loc varchar2(13),
5 emps emp_tab_type
6 )
7 nested table emps store as emps_nt;
Table created.
SQL>
SQL> alter table emps_nt add constraint emps_empno_unique
2 unique(empno)
3 /
Table altered.
SQL>
SQL> insert into dept_and_emp
2 select dept.*,
3 CAST( multiset( select empno, ename, job, mgr, hiredate, sal, comm
4 from emp
5 where emp.deptno = dept.deptno ) AS emp_tab_type )
6 from dept
7 /
4 rows created.
SQL>
SQL> select d.deptno, d.dname, emp.*
2 from dept_and_emp D, table(d.emps) emp
3 /
DEPTNO DNAME EMPNO ENAME JOB MGR HIREDATE SAL COMM
---------- -------------- ---------- ---------- --------- ---------- --------- ---------- ----------
10 ACCOUNTING 7782 CLARK MANAGER 7839 09-JUN-81 2450
10 ACCOUNTING 7839 KING PRESIDENT 17-NOV-81 5000
10 ACCOUNTING 7934 MILLER CLERK 7782 23-JAN-82 1300
20 RESEARCH 7369 SMITH CLERK 7902 17-DEC-80 800
20 RESEARCH 7566 JONES MANAGER 7839 02-APR-81 2975
20 RESEARCH 7788 SCOTT ANALYST 7566 09-DEC-82 3000
20 RESEARCH 7876 ADAMS CLERK 7788 12-JAN-83 1100
20 RESEARCH 7902 FORD ANALYST 7566 03-DEC-81 3000
30 SALES 7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300
30 SALES 7521 WARD SALESMAN 7698 22-FEB-81 1250 500
30 SALES 7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400
DEPTNO DNAME EMPNO ENAME JOB MGR HIREDATE SAL COMM
---------- -------------- ---------- ---------- --------- ---------- --------- ---------- ----------
30 SALES 7698 BLAKE MANAGER 7839 01-MAY-81 2850
30 SALES 7844 TURNER SALESMAN 7698 08-SEP-81 1500 0
30 SALES 7900 JAMES CLERK 7698 03-DEC-81 950
14 rows selected.
SQL>
SQL> drop table dept cascade constraint;
Table dropped.
SQL> drop table emp;
Table dropped.
SQL> drop table dept_and_emp;
Table dropped.
SQL> drop type emp_tab_type;
Type dropped.
SQL> drop type emp_type;
Type dropped.
SQL>
SQL>
The CAST Function
The "THE" function is one way to get individual members from the VARRAY.
The CAST function is used to convert collection types to ordinary, common types in Oracle. CAST may be used in a SELECT to explicitly define that a collection type is being converted:
SQL>
SQL> CREATE OR REPLACE TYPE mem_type IS VARRAY(10) of VARCHAR2(15)
2 /
Type created.
SQL>
SQL>
SQL> CREATE TABLE club (Name VARCHAR2(10),
2 Address VARCHAR2(20),
3 City VARCHAR2(20),
4 Phone VARCHAR2(8),
5 Members mem_type)
6 /
Table created.
SQL>
SQL>
SQL>
SQL> INSERT INTO club VALUES ("AL","111 First St.","Mobile",
2 "222-2222", mem_type("Brenda","Richard"));
1 row created.
SQL>
SQL> INSERT INTO club VALUES ("FL","222 Second St.","Orlando",
2 "333-3333", mem_type("Gen","John","Steph","JJ"));
1 row created.
SQL>
SQL>
SQL>
SQL>
SQL> SELECT COLUMN_VALUE FROM
2 THE(SELECT CAST(c.members as mem_type)
3 FROM club c
4 WHERE c.name = "FL");
COLUMN_VALUE
---------------
Gen
John
Steph
JJ
SQL>
SQL>
SQL>
SQL>
SQL> drop table club;
Table dropped.
SQL> drop type mem_type;
Type dropped.
The CAST function converts an object type (such as a VARRAY) into a common type that can be queried. Oracle 10g automatically converts the VARRAY without the CAST.
The CAST function may also be used with the MULTISET function to perform DML operations on VARRAYs. MULTISET is the "reverse" of CAST in that MULTISET converts a nonobject set of data to an object set. Suppose we create a new table of names:
SQL>
SQL>
SQL> CREATE OR REPLACE TYPE mem_type IS VARRAY(10) of VARCHAR2(15)
2 /
Type created.
SQL>
SQL>
SQL> CREATE TABLE club (Name VARCHAR2(10),
2 Address VARCHAR2(20),
3 City VARCHAR2(20),
4 Phone VARCHAR2(8),
5 Members mem_type)
6 /
Table created.
SQL>
SQL>
SQL>
SQL> INSERT INTO club VALUES ("AL","111 First St.","Mobile",
2 "222-2222", mem_type("Brenda","Richard"));
1 row created.
SQL>
SQL> INSERT INTO club VALUES ("FL","222 Second St.","Orlando",
2 "333-3333", mem_type("Gen","John","Steph","JJ"));
1 row created.
SQL>
SQL>
SQL>
SQL>
SQL> SELECT COLUMN_VALUE FROM
2 THE(SELECT CAST(c.members as mem_type)
3 FROM club c
4 WHERE c.name = "FL");
COLUMN_VALUE
---------------
Gen
John
Steph
JJ
SQL>
SQL>
SQL>
SQL> CREATE TABLE newnames (n varchar2(20))
2 /
Table created.
SQL> INSERT INTO newnames VALUES ("Beryl")
2 /
1 row created.
SQL> INSERT INTO newnames VALUES ("Fred")
2 /
1 row created.
SQL> SELECT *
2 FROM newnames
3 /
N
--------------------
Beryl
Fred
SQL>
SQL> INSERT INTO club VALUES ("VA",null,null,null,null)
2 /
1 row created.
SQL> UPDATE club SET members =
2 CAST(MULTISET(SELECT n FROM newnames) as mem_type)
3 WHERE name = "VA"
4 /
1 row updated.
SQL>
SQL> select * from club;
NAME ADDRESS CITY PHONE
---------- -------------------------------------------------- -------------------- --------
MEMBERS
-------------------------------------------------------------------------------------------
AL 111 First St. Mobile 222-2222
MEM_TYPE("Brenda", "Richard")
FL 222 Second St. Orlando 333-3333
MEM_TYPE("Gen", "John", "Steph", "JJ")
VA
MEM_TYPE("Beryl", "Fred")
SQL>
SQL> INSERT INTO club VALUES("MD",null, null,null,
2 CAST(MULTISET(SELECT * FROM newnames) as mem_type))
3 /
1 row created.
SQL>
SQL> select * from club;
NAME ADDRESS CITY PHONE
---------- -------------------------------------------------- -------------------- --------
MEMBERS
-------------------------------------------------------------------------------------------
AL 111 First St. Mobile 222-2222
MEM_TYPE("Brenda", "Richard")
FL 222 Second St. Orlando 333-3333
MEM_TYPE("Gen", "John", "Steph", "JJ")
VA
MEM_TYPE("Beryl", "Fred")
MD
MEM_TYPE("Beryl", "Fred")
SQL>
SQL>
SQL> drop table newnames;
Table dropped.
SQL>
SQL> drop table club;
Table dropped.
SQL> drop type mem_type;
Type dropped.
Transform a collection into a table and reference it in a SQL query.
You do this by casting the collection to a table.
SQL> -- create demo table
SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL,
3 First_Name VARCHAR2(10 BYTE),
4 Last_Name VARCHAR2(10 BYTE),
5 Start_Date DATE,
6 End_Date DATE,
7 Salary Number(8,2),
8 City VARCHAR2(10 BYTE),
9 Description VARCHAR2(15 BYTE)
10 )
11 /
Table created.
SQL>
SQL> -- prepare data
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created.
SQL>
SQL>
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---- -------------------- -------------------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer
02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester
03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester
04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager
05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester
06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester
07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager
08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester
8 rows selected.
SQL>
SQL>
SQL>
SQL>
SQL> create or replace type emp2_oty is object (empNo NUMBER,eName VARCHAR2(10))
2 /
Type created.
SQL>
SQL> create or replace type emp2_nt is table of emp2_oty
2 /
Type created.
SQL>
SQL> create or replace function f_getEmps_nt(i_deptNo number, i_hireDate DATE)
2 return emp2_nt
3 is
4 v_emp2_nt emp2_nt:=emp2_nt();
5 cursor c_emp is select * from employee;
6 begin
7 for r_emp in c_emp
8 loop
9 if i_deptNo is null then
10 if i_hireDate is null or to_char(i_hireDate,"mm")= to_char(r_emp.start_Date,"mm")
11 then
12 v_emp2_nt.extend;
13 v_emp2_nt(v_emp2_nt.last):= emp2_oty(r_emp.id, r_emp.first_Name);
14 end if;
15 elsif i_deptNo=r_emp.id then
16 v_emp2_nt.extend;
17 v_emp2_nt(v_emp2_nt.last):= emp2_oty(r_emp.id, r_emp.first_name);
18 end if;
19 end loop;
20 return v_emp2_nt;
21 end;
22 /
Function created.
SQL>
SQL>
SQL>
SQL> select t.*
2 from table (cast (f_getEmps_nt (20,null) as emp2_nt)) t
3 /
no rows selected
SQL>
SQL> create or replace package pkg_globals
2 is
3 v_currentDeptno number:=10;
4 function f_getCurrDeptNo return number;
5 procedure p_setCurrDeptNo(i_nr number);
6
7 v_currentHireDate date:=sysdate;
8 function f_getCurrHireDate return date;
9 procedure p_setCurrHireDate(i_dt date);
10 end;
11 /
Package created.
SQL>
SQL> create or replace package body pkg_globals
2 is
3 function f_getCurrDeptNo return number is
4 begin
5 return v_currentDeptNo;
6 end;
7 procedure p_setCurrDeptNo(i_nr number) is
8 begin
9 v_currentDeptNo:=i_nr;
10 end;
11 function f_getCurrHireDate return date is
12 begin
13 return v_currentHireDate;
14 end;
15 procedure p_setCurrHireDate(i_dt date) is
16 begin
17 v_currentHireDate:=i_dt;
18 end;
19 end;
20 /
Package body created.
SQL>
SQL>
SQL> create or replace view v_getEmps
2 as
3 select *
4 from table(cast (f_getEmps_nt (pkg_globals.f_getCurrDeptNo,pkg_globals.f_getCurrHireDate) as emp2_nt));
View created.
SQL>
SQL>
SQL> drop type emp2_nt;
Type dropped.
SQL>
SQL> drop type emp2_oty;
Type dropped.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.
SQL>
SQL>
Use view to cast records in result set to a type
SQL>
SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
2 ENAME VARCHAR2(10),
3 JOB VARCHAR2(9),
4 MGR NUMBER(4),
5 HIREDATE DATE,
6 SAL NUMBER(7, 2),
7 COMM NUMBER(7, 2),
8 DEPTNO NUMBER(2));
Table created.
SQL>
SQL>
SQL> INSERT INTO EMP VALUES (7369, "SMITH", "CLERK", 7902, TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7499, "ALLEN", "SALESMAN", 7698, TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7521, "WARD", "SALESMAN", 7698, TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7566, "JONES", "MANAGER", 7839, TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10);
1 row created.
SQL>
SQL>
SQL>
SQL>
SQL> CREATE TABLE DEPT (DEPTNO NUMBER(2),DNAME VARCHAR2(14),LOC VARCHAR2(13) );
Table created.
SQL>
SQL> INSERT INTO DEPT VALUES (10, "ACCOUNTING", "NEW YORK");
1 row created.
SQL> INSERT INTO DEPT VALUES (20, "RESEARCH", "DALLAS");
1 row created.
SQL> INSERT INTO DEPT VALUES (30, "SALES", "CHICAGO");
1 row created.
SQL> INSERT INTO DEPT VALUES (40, "OPERATIONS", "BOSTON");
1 row created.
SQL>
SQL> create or replace type emp_type
2 as object
3 (empno number(4),
4 ename varchar2(10),
5 job varchar2(9),
6 mgr number(4),
7 hiredate date,
8 sal number(7, 2),
9 comm number(7, 2)
10 );
11 /
Type created.
SQL>
SQL>
SQL> create or replace type emp_tab_type
2 as table of emp_type
3 /
Type created.
SQL>
SQL>
SQL> create or replace type dept_type
2 as object
3 ( deptno number(2),
4 dname varchar2(14),
5 loc varchar2(13),
6 emps emp_tab_type
7 )
8 /
Type created.
SQL>
SQL> create or replace view dept_or
2 of dept_type
3 with object identifier(deptno)
4 as
5 select deptno, dname, loc,
6 cast ( multiset (
7 select empno, ename, job, mgr, hiredate, sal, comm
8 from emp
9 where emp.deptno = dept.deptno )
10 as emp_tab_type )
11 from dept
12 /
View created.
SQL>
SQL> declare
2 l_emps emp_tab_type;
3 begin
4 select p.emps into l_emps from dept_or p where deptno = 10;
5
6 for i in 1 .. l_emps.count
7 loop
8 l_emps(i).ename := lower(l_emps(i).ename);
9 end loop;
10
11 update dept_or
12 set emps = l_emps
13 where deptno = 10;
14 end;
15 /
declare
*
ERROR at line 1:
ORA-01733: virtual column not allowed here
ORA-06512: at line 11
SQL>
SQL> drop type dept_type;
Type dropped.
SQL>
SQL> drop type emp_tab_type;
Type dropped.
SQL>
SQL> drop type emp_type;
Type dropped.
SQL>
SQL> drop table emp;
Table dropped.
SQL>
SQL> drop table dept;
Table dropped.