What is collection and its attributea with example.

Collection:-
Collection is an Ordered group of elements, all of the same type.

Attributes of Collection

1.  FIRST
2.  LAST
3.  COUNT
4.  DELETE
5.  EXTAND
6.  TRIM
7.  NEXT
8.  EXIST
9.  PRIOR
10. LIMIT

Types of Collection

1.  Varray
2.  Nested Table
3.  PL/SQL Table or Associate Array

Varray:-
Varray stands of variable size array.Varray can be stored in the column of table.

Syntax of Varray:- Type type_name is VARRAY(length) of data_type;

Examples of Varray

1.

DECLARE
TYPE L_VAR IS VARRAY(10) OF VARCHAR2(3);
L_VAR1 L_VAR;
BEGIN
L_VAR1:=L_VAR(‘A’,’B’,’C’,’D’,’E’,’F’,’G’,’H’);
FOR I IN 1..8
LOOP
DBMS_OUTPUT.PUT_LINE(L_VAR1(I));
END LOOP;
END;

2.

DECLARE
TYPE L_VAR IS VARRAY(10) OF VARCHAR2(3);
L_VAR1 L_VAR;
BEGIN
L_VAR1:=L_VAR(‘A’,’B’,’C’,’D’,’E’,’F’,’G’,’H’);
FOR I IN L_VAR1.FIRST..L_VAR1.COUNT
LOOP
DBMS_OUTPUT.PUT_LINE(L_VAR1(I));
END LOOP;
END;

3.

DECLARE
TYPE L_VAR IS VARRAY(10) OF VARCHAR2(10);
L_VAR1 L_VAR:= L_VAR();
BEGIN
L_VAR1.EXTEND;
L_VAR1(1):=’HELLO’;
L_VAR1.EXTEND;
L_VAR1(2):= ‘ORACLE’;
L_VAR1.EXTEND;
L_VAR1(3):=’JAVA’;
L_VAR1.EXTEND;
L_VAR1(4):= ‘OAF’;
FOR I IN 1..4
LOOP
DBMS_OUTPUT.PUT_LINE(L_VAR1(I));
END LOOP;
END;

4.

DECLARE
CURSOR C1 IS
SELECT PO_HEADER_ID
FROM PO_HEADERS_ALL
WHERE ROWNUM<=100;
TYPE L_HDR IS VARRAY(100) OF PO_HEADERS_ALL.PO_HEADER_ID%TYPE;
L_HDR1 L_HDR:= L_HDR();
COUNTER NUMBER:=0;
BEGIN
FOR I IN C1
LOOP
COUNTER:= COUNTER+1;
L_HDR1.EXTEND;
L_HDR1(COUNTER):= I.PO_HEADER_ID;
DBMS_OUTPUT.PUT_LINE('PO_HEADER_ID IS '||L_HDR1(COUNTER));
END LOOP;
END;

5.

DECLARE
CURSOR C1 IS
SELECT PO_HEADER_ID
FROM PO_HEADERS_ALL
WHERE ROWNUM<=100;
TYPE L_HDR IS VARRAY(100) OF PO_HEADERS_ALL.PO_HEADER_ID%TYPE;
L_HDR1 L_HDR:=L_HDR();
COUNTER NUMBER:=0;
BEGIN
OPEN C1;
FOR I IN 1..100
LOOP
COUNTER:= COUNTER+1;
L_HDR1.EXTEND;
FETCH C1 INTO L_HDR1(COUNTER);
DBMS_OUTPUT.PUT_LINE('PO_HEADER_ID IS '||L_HDR1(COUNTER));
END LOOP;
END;

Nested Table:-
Nested table is like a one-dimensional array.

Syntax of Nested Table:-   TYPE type_name IS TABLE OF data_type;

Example of Nested Table

1.

DECLARE
TYPE L_TAB IS TABLE OF NUMBER;
L_TAB1 L_TAB;
BEGIN
L_TAB1:= L_TAB(1,2,3,4,5);
FOR I IN 1..5
LOOP
DBMS_OUTPUT.PUT_LINE(L_TAB1(I));
END LOOP;
END;

2.

DECLARE
TYPE L_TAB IS TABLE OF NUMBER;
L_TAB1 L_TAB;
BEGIN
L_TAB1:= L_TAB(1,2,3,4,5);
FOR I IN L_TAB.FIRST..L_TAB1.LAST
LOOP
DBMS_OUTPUT.PUT_LINE(L_TAB1(I));
END LOOP;
END;

3.

DECLARE
CURSOR C_HDR IS
SELECT PO_HEADER_ID
FROM PO_HEADERS_ALL
WHERE ROWNUM<=100;
TYPE L_TAB_HDR IS TABLE OF PO_HEADERS_ALL.PO_HEADER_ID%TYPE;
L_HDR L_TAB_HDR:= L_TAB_HDR();
COUNTER NUMBER:=0;
BEGIN
FOR I IN C_HDR
LOOP
COUNTER:= COUNTER+1;
L_HDR.EXTEND;
L_HDR(COUNTER):= I.PO_HEADER_ID;
DBMS_OUTPUT.PUT_LINE(L_HDR(COUNTER));
END LOOP;
END;

4.

DECLARE
CURSOR C_HDR IS
SELECT PO_HEADER_ID
FROM PO_HEADERS_ALL
WHERE ROWNUM<=100;
TYPE L_TAB_HDR IS TABLE OF PO_HEADERS_ALL.PO_HEADER_ID%TYPE;
L_HDR L_TAB_HDR:= L_TAB_HDR();
COUNTER NUMBER:=0;
BEGIN
OPEN C_HDR;
FOR I IN 1..100
LOOP
COUNTER:= COUNTER+1;
L_HDR.EXTEND;
FETCH C_HDR INTO L_HDR(COUNTER);
DBMS_OUTPUT.PUT_LINE(L_HDR(COUNTER));
END LOOP;
END;

5.

DECLARE
CURSOR C_HDR IS
SELECT *
FROM PO_HEADERS_ALL
WHERE ROWNUM<=100;
TYPE L_TAB_HDR IS TABLE OF PO_HEADERS_ALL%ROWTYPE;
L_HDR L_TAB_HDR:= L_TAB_HDR();
COUNTER NUMBER:=0;
BEGIN
OPEN C_HDR;
FOR I IN 1..100
LOOP
COUNTER:= COUNTER+1;
L_HDR.EXTEND;
FETCH C_HDR INTO L_HDR(COUNTER);
DBMS_OUTPUT.PUT_LINE('HEADER ID'||CHR(9)||L_HDR(COUNTER).PO_HEADER_ID||CHR(9)||'PO NUMBER'||CHR(9)||L_HDR(COUNTER).SEGMENT1);
END LOOP;
END;

PL/SQL Table:-
PL/SQL Table helps you moves bulk data. They can store column or rows of Oracle Data.

Syntax:- TYPE type_name is TABLE OF data_type
INDEX BY NUMBER/VARCHAR2/PLS_INTRGER/BINARY_INTEGER;

Example:-

1.

DECLARE
TYPE L_TAB IS TABLE OF NUMBER
INDEX BY PLS_INTEGER;
L_TAB1 L_TAB;
BEGIN
L_TAB1(1):=1;
L_TAB1(2):=2;
L_TAB1(3):=3;
L_TAB1(4):=4;
L_TAB1(5):=5;
FOR I IN L_TAB1.FIRST..L_TAB1.LAST
LOOP
DBMS_OUTPUT.PUT_LINE(L_TAB1(I));
END LOOP;
END;

2.

DECLARE
CURSOR C_HDR IS
SELECT PO_HEADER_ID,SEGMENT1
FROM PO_HEADERS_ALL
WHERE ROWNUM<=100;
TYPE L_TAB_HDR IS TABLE OF PO_HEADERS_ALL.SEGMENT1%TYPE
INDEX BY PLS_INTEGER;
L_HDR L_TAB_HDR;
COUNTER NUMBER:=0;
BEGIN
FOR I IN C_HDR
LOOP
COUNTER:= COUNTER+1;
L_HDR(COUNTER):= I.SEGMENT1;
DBMS_OUTPUT.PUT_LINE(L_HDR(COUNTER));
END LOOP;
END;

3.

DECLARE
CURSOR C_HDR IS
SELECT PO_HEADER_ID,SEGMENT1
FROM PO_HEADERS_ALL
WHERE ROWNUM<=100;
TYPE L_TAB_HDR IS TABLE OF PO_HEADERS_ALL.SEGMENT1%TYPE
INDEX BY PLS_INTEGER;
L_HDR L_TAB_HDR;
COUNTER NUMBER:=0;
BEGIN
FOR I IN C_HDR
LOOP
COUNTER:= COUNTER+1;
L_HDR(COUNTER):= I.SEGMENT1;
END LOOP;
FOR J IN 1..COUNTER
LOOP
DBMS_OUTPUT.PUT_LINE(L_HDR(J));
END LOOP;
END;

———————————————–

DECLARE
TYPE L_EMP_REC IS RECORD(
L_EMP_ID NUMBER,
L_NAME VARCHAR2(20),
L_SALARY NUMBER);
TYPE L_TAB IS TABLE OF L_EMP_REC;
L_TAB1 L_TAB;
BEGIN
SELECT EMPLOYEE_ID,LAST_NAME,SALARY
BULK COLLECT INTO L_TAB1
FROM EMPLOYEES;
FOR I IN L_TAB1.FIRST..L_TAB1.COUNT
LOOP
DBMS_OUTPUT.PUT_LINE(L_TAB1(I).L_EMP_ID||CHR(9)||L_TAB1(I).L_NAME);
END LOOP;
END;

DECLARE
TYPE L_EMP_REC IS RECORD(L_EMP_ID NUMBER,
L_NAME VARCHAR2(20),
L_DEPT_ID NUMBER,
L_SAL NUMBER,
L_HIRE_DATE DATE
);
TYPE L_TAB IS TABLE OF L_EMP_REC;
L_TAB1 L_TAB;
CURSOR C1 IS
SELECT EMPLOYEE_ID,
LAST_NAME,
DEPARTMENT_ID,
SALARY,
HIRE_DATE
FROM EMPLOYEES;
BEGIN
OPEN C1;
FETCH C1 BULK COLLECT INTO L_TAB1;
FOR I IN L_TAB1.FIRST..L_TAB1.COUNT
LOOP
DBMS_OUTPUT.PUT_LINE(L_TAB1(I).L_EMP_ID||CHR(9)||L_TAB1(I).L_NAME);
END LOOP;
END;

————————————

Package:-
Package is the collection of database objects i.e. Procedure, Function, Anomous block.

Advantages:-
1) Modularity
2) Security
3) Easy to Maintenance
4) Function overLoading

Syntax:-
CREATE OR REPLACE PACKAGE package_name
IS
PROCEDURE PROC1;
……
FUNCTION FUN1
RETURN NUMBER;
………
END package_name;

CREATE OR REPLACE PACKAGE BODY package_name
IS
PROCEDURE PROC1
IS
BEGIN
STATEMENT;
END PROC1;
FUNCTION FUN1
RETURN NUMBER
IS
BEGIN
STATEMENT;
RETURN value;
END FUN1;
END package_name;

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