1. Overview
This document talks about the steps to working with Oracle nested tables.Nested table is awesome feature of Oracle. You can create table inside a table, Which means one column can be treated as a table. Nested tables are faster than the parent child table relationship.
2. Technologies and Tools Used
The following technology has been used to achieve requirement
- Oracle PLSQL
3. Use Case
Assume that there is a requirement to achieve the customer needs by using nested tables .
4. Architecture
Step 1:
Create Object TYPE:
CREATE OR REPLACE TYPE emp_rec_type AS OBJECT
(
EMPNO NUMBER (4),
ENAME VARCHAR2 (10 BYTE),
JOB VARCHAR2 (9 BYTE),
MGR NUMBER (4),
HIREDATE DATE,
SAL NUMBER (7, 2),
COMM NUMBER (7, 2)
);
Create Table type :
CREATE TYPE emp_table_type AS TABLE OF emp_rec_type;
Create Table with Object type:
CREATE TABLE dept_details
( deptno NUMBER (2),
dname VARCHAR2 (14 byte),
loc VARCHAR2 (13 byte),
employees EMP_TABLE_TYPE
)nested TABLE employees store AS emp_tab_index;
emp_tab_index is nested table index
Need to create table and insert data in dept and emp tables (If not exist in db )
CREATE TABLE DEPT
(
DEPTNO NUMBER (2) CONSTRAINT PK_DEPT PRIMARY KEY,
DNAME VARCHAR2 (14),
LOC VARCHAR2 (13)
);
/
CREATE TABLE EMP
(
EMPNO NUMBER (4) CONSTRAINT PK_EMP PRIMARY KEY,
ENAME VARCHAR2 (10),
JOB VARCHAR2 (9),
MGR NUMBER (4),
HIREDATE DATE,
SAL NUMBER (7, 2),
COMM NUMBER (7, 2),
DEPTNO NUMBER (2) CONSTRAINT FK_DEPTNO REFERENCES DEPT
);
/
INSERT INTO DEPT VALUES (10,’ACCOUNTING’,’NEW YORK’);
INSERT INTO DEPT VALUES (20,’RESEARCH’,’DALLAS’);
INSERT INTO DEPT VALUES (30,’SALES’,’CHICAGO’);
INSERT INTO DEPT VALUES (40,’OPERATIONS’,’BOSTON’);
INSERT INTO EMP VALUES (7369,’SMITH’,’CLERK’,7902,to_date(’17-12-1980′,’dd-mm-yyyy’),800,NULL,20);
INSERT INTO EMP VALUES (7499,’ALLEN’,’SALESMAN’,7698,to_date(’20-2-1981′,’dd-mm-yyyy’),1600,300,30);
INSERT INTO EMP VALUES (7521,’WARD’,’SALESMAN’,7698,to_date(’22-2-1981′,’dd-mm-yyyy’),1250,500,30);
INSERT INTO EMP VALUES (7566,’JONES’,’MANAGER’,7839,to_date(‘2-4-1981′,’dd-mm-yyyy’),2975,NULL,20);
INSERT INTO EMP VALUES (7654,’MARTIN’,’SALESMAN’,7698,to_date(’28-9-1981′,’dd-mm-yyyy’),1250,1400,30);
INSERT INTO EMP VALUES (7698,’BLAKE’,’MANAGER’,7839,to_date(‘1-5-1981′,’dd-mm-yyyy’),2850,NULL,30);
INSERT INTO EMP VALUES (7782,’CLARK’,’MANAGER’,7839,to_date(‘9-6-1981′,’dd-mm-yyyy’),2450,NULL,10);
INSERT INTO EMP VALUES (7788,’SCOTT’,’ANALYST’,7566,to_date(’13-JUL-87′,’dd-mm-rr’)-85,3000,NULL,20);
INSERT INTO EMP VALUES (7839,’KING’,’PRESIDENT’,NULL,to_date(’17-11-1981′,’dd-mm-yyyy’),5000,NULL,10);
INSERT INTO EMP VALUES (7844,’TURNER’,’SALESMAN’,7698,to_date(‘8-9-1981′,’dd-mm-yyyy’),1500,0,30);
INSERT INTO EMP VALUES (7876,’ADAMS’,’CLERK’,7788,to_date(’13-JUL-87′, ‘dd-mm-rr’)-51,1100,NULL,20);
INSERT INTO EMP VALUES (7900,’JAMES’,’CLERK’,7698,to_date(‘3-12-1981′,’dd-mm-yyyy’),950,NULL,30);
INSERT INTO EMP VALUES (7902,’FORD’,’ANALYST’,7566,to_date(‘3-12-1981′,’dd-mm-yyyy’),3000,NULL,20);
INSERT INTO EMP VALUES (7934,’MILLER’,’CLERK’,7782,to_date(’23-1-1982′,’dd-mm-yyyy’),1300,NULL,10);
/
COMMIT;
Step2:
INSERT into Nested table:
DECLARE
CURSOR c_dept
IS
SELECT deptno, dname, loc FROM dept;
TYPE l_dept_rec_type IS RECORD
( DEPTNO dept.deptno%TYPE,
DNAME dept.DNAME%TYPE,
LOC dept.LOC%TYPE
);
TYPE l_dept_tab_type IS TABLE OF l_dept_rec_type;
l_dept_no l_dept_tab_type;
CURSOR c_emp_list (P_DEPTNO DEPT.DEPTNO%TYPE)
IS
SELECT emp_rec_type (EMPNO,
ENAME,
JOB,
MGR,
HIREDATE,
SAL,
COMM)
FROM EMP
WHERE deptno = P_DEPTNO;
l_EMP_list_tab emp_table_type;
BEGIN
OPEN c_dept;
FETCH c_dept
BULK COLLECT INTO l_dept_no;
CLOSE c_dept;
FOR i IN l_dept_no.FIRST .. l_dept_no.LAST
LOOP
OPEN c_emp_list (l_dept_no (i).deptno);
FETCH c_emp_list
BULK COLLECT INTO l_EMP_list_tab;
CLOSE c_emp_list;
INSERT INTO dept_details (DEPTNO,
DNAME,
LOC,
employees)
VALUES (l_dept_no (i).deptno,
l_dept_no (i).dname,
l_dept_no (i).loc,
l_EMP_list_tab);
END LOOP;
commit;
END;
Step3:
Select Data from nested table:
SELECT ee.empno,
ee.ename,
ee.comm
FROM dept_details dd,
TABLE (employees) ee
WHERE ee.empno = 7788;
Step4:
UPDATE data in Nested Table:
UPDATE TABLE (SELECT dept_details.employees
FROM dept_details
WHERE dept_details.deptno = 10)
SET comm = 9000
WHERE empno = 7839;
Step5:
Delete from Nested table:
DELETE TABLE (SELECT dept_details.employees
FROM dept_details
WHERE dept_details.deptno = 10)
WHERE empno = 7839;
