PL/SQL - Collections

PL/SQL Collections:

A collection is an ordered group of elements having the same data type. Each element is identified by a unique subscript that represents its position in the collection.

PL/SQL provides three collection types −

• Index-by tables or Associative array
• Nested table
• Variable-size array or Varray

Oracle documentation provides the following characteristics for each type of collections −

Collection Type	Number of Elements	Subscript Type	Dense or Sparse	Where Created	Can Be Object Type Attribute
Associative array (or index-by table)	Unbounded	String or integer	Either	Only in PL/SQL block	No
Nested table	Unbounded	Integer	Starts dense, can become sparse	Either in PL/SQL block or at schema level	Yes
Variablesize array (Varray)	Bounded	Integer	Always dense	Either in PL/SQL block or at schema level	Yes

We have already discussed varray in the chapter 'PL/SQL arrays'. In this chapter, we will discuss the PL/SQL tables.

Both types of PL/SQL tables, i.e., the index-by tables and the nested tables have the same structure and their rows are accessed using the subscript notation. However, these two types of tables differ in one aspect; the nested tables can be stored in a database column and the index-by tables cannot.

Index-By Table

An index-by table (also called an associative array) is a set of key-value pairs. Each key is unique and is used to locate the corresponding value. The key can be either an integer or a string.

An index-by table is created using the following syntax. Here, we are creating an index-by table named table_name, the keys of which will be of the subscript_type and associated values will be of the element_type

TYPE type_name IS TABLE OF element_type [NOT NULL] INDEX BY subscript_type; 
 
table_name type_name;

Example

Following example shows how to create a table to store integer values along with names and later it prints the same list of names.

DECLARE 
   TYPE salary IS TABLE OF NUMBER INDEX BY VARCHAR2(20); 
   salary_list salary; 
   name   VARCHAR2(20); 
BEGIN 
   -- adding elements to the table 
   salary_list('Rajnish') := 62000; 
   salary_list('Minakshi') := 75000; 
   salary_list('Martin') := 100000; 
   salary_list('James') := 78000;  
   
   -- printing the table 
   name := salary_list.FIRST; 
   WHILE name IS NOT null LOOP 
      dbms_output.put_line 
      ('Salary of ' || name || ' is ' || TO_CHAR(salary_list(name))); 
      name := salary_list.NEXT(name); 
   END LOOP; 
END; 
/

When the above code is executed at the SQL prompt, it produces the following result −

Salary of James is 78000 
Salary of Martin is 100000 
Salary of Minakshi is 75000 
Salary of Rajnish is 62000  

PL/SQL procedure successfully completed.

Example

Elements of an index-by table could also be a %ROWTYPE of any database table or %TYPE of any database table field. The following example illustrates the concept. We will use the CUSTOMERS table stored in our database as −

Select * from customers;  

+----+----------+-----+-----------+----------+ 
| ID | NAME     | AGE | ADDRESS   | SALARY   | 
+----+----------+-----+-----------+----------+ 
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 | 
|  2 | Khilan   |  25 | Delhi     |  1500.00 | 
|  3 | kaushik  |  23 | Kota      |  2000.00 | 
|  4 | Chaitali |  25 | Mumbai    |  6500.00 | 
|  5 | Hardik   |  27 | Bhopal    |  8500.00 | 
|  6 | Komal    |  22 | MP        |  4500.00 | 
+----+----------+-----+-----------+----------+  

DECLARE 
   CURSOR c_customers is 
      select name from customers; 

   TYPE c_list IS TABLE of customers.Name%type INDEX BY binary_integer; 
   name_list c_list; 
   counter integer :=0; 
BEGIN 
   FOR n IN c_customers LOOP 
      counter := counter +1; 
      name_list(counter) := n.name; 
      dbms_output.put_line('Customer('||counter||'):'||name_lis t(counter)); 
   END LOOP; 
END; 
/ 

When the above code is executed at the SQL prompt, it produces the following result −

Customer(1): Ramesh  
Customer(2): Khilan  
Customer(3): kaushik     
Customer(4): Chaitali  
Customer(5): Hardik  
Customer(6): Komal  

PL/SQL procedure successfully completed

Nested Tables

A nested table is like a one-dimensional array with an arbitrary number of elements. However, a nested table differs from an array in the following aspects −

• An array has a declared number of elements, but a nested table does not. The size of a nested table can increase dynamically.

• An array is always dense, i.e., it always has consecutive subscripts. A nested array is dense initially, but it can become sparse when elements are deleted from it.

A nested table is created using the following syntax −

TYPE type_name IS TABLE OF element_type [NOT NULL]; 
 
table_name type_name; 

This declaration is similar to the declaration of an index-by table, but there is no INDEX BY clause.

A nested table can be stored in a database column. It can further be used for simplifying SQL operations where you join a single-column table with a larger table. An associative array cannot be stored in the database.

Example

The following examples illustrate the use of nested table −

DECLARE 
   TYPE names_table IS TABLE OF VARCHAR2(10); 
   TYPE grades IS TABLE OF INTEGER;  
   names names_table; 
   marks grades; 
   total integer; 
BEGIN 
   names := names_table('Kavita', 'Pritam', 'Ayan', 'Rishav', 'Aziz'); 
   marks:= grades(98, 97, 78, 87, 92); 
   total := names.count; 
   dbms_output.put_line('Total '|| total || ' Students'); 
   FOR i IN 1 .. total LOOP 
      dbms_output.put_line('Student:'||names(i)||', Marks:' || marks(i)); 
   end loop; 
END; 
/  

When the above code is executed at the SQL prompt, it produces the following result −

Total 5 Students 
Student:Kavita, Marks:98 
Student:Pritam, Marks:97 
Student:Ayan, Marks:78 
Student:Rishav, Marks:87 
Student:Aziz, Marks:92  

PL/SQL procedure successfully completed. 

Example

Elements of a nested table can also be a %ROWTYPE of any database table or %TYPE of any database table field. The following example illustrates the concept. We will use the CUSTOMERS table stored in our database as −

Select * from customers;  

+----+----------+-----+-----------+----------+ 
| ID | NAME     | AGE | ADDRESS   | SALARY   | 
+----+----------+-----+-----------+----------+ 
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 | 
|  2 | Khilan   |  25 | Delhi     |  1500.00 | 
|  3 | kaushik  |  23 | Kota      |  2000.00 | 
|  4 | Chaitali |  25 | Mumbai    |  6500.00 | 
|  5 | Hardik   |  27 | Bhopal    |  8500.00 | 
|  6 | Komal    |  22 | MP        |  4500.00 | 
+----+----------+-----+-----------+----------+ 

DECLARE 
   CURSOR c_customers is  
      SELECT  name FROM customers;  
   TYPE c_list IS TABLE of customerS.No.ame%type; 
   name_list c_list := c_list(); 
   counter integer :=0; 
BEGIN 
   FOR n IN c_customers LOOP 
      counter := counter +1; 
      name_list.extend; 
      name_list(counter)  := n.name; 
      dbms_output.put_line('Customer('||counter||'):'||name_list(counter)); 
   END LOOP; 
END; 
/ 

When the above code is executed at the SQL prompt, it produces the following result −

Customer(1): Ramesh  
Customer(2): Khilan  
Customer(3): kaushik     
Customer(4): Chaitali  
Customer(5): Hardik  
Customer(6): Komal  

PL/SQL procedure successfully completed. 

Collection Methods

PL/SQL provides the built-in collection methods that make collections easier to use. The following table lists the methods and their purpose −

S.No	Method Name & Purpose
1	EXISTS(n) Returns TRUE if the nth element in a collection exists; otherwise returns FALSE.
2	COUNT Returns the number of elements that a collection currently contains.
3	LIMIT Checks the maximum size of a collection.
4	FIRST Returns the first (smallest) index numbers in a collection that uses the integer subscripts.
5	LAST Returns the last (largest) index numbers in a collection that uses the integer subscripts.
6	PRIOR(n) Returns the index number that precedes index n in a collection.
7	NEXT(n) Returns the index number that succeeds index n.
8	EXTEND Appends one null element to a collection.
9	EXTEND(n) Appends n null elements to a collection.
10	EXTEND(n,i) Appends n copies of the ith element to a collection.
11	TRIM Removes one element from the end of a collection.
12	TRIM(n) Removes n elements from the end of a collection.
13	DELETE Removes all elements from a collection, setting COUNT to 0.
14	DELETE(n) Removes the nth element from an associative array with a numeric key or a nested table. If the associative array has a string key, the element corresponding to the key value is deleted. If n is null, DELETE(n) does nothing.
15	DELETE(m,n) Removes all elements in the range m..n from an associative array or nested table. If m is larger than n or if m or n is null, DELETE(m,n) does nothing.

Collection Exceptions

The following table provides the collection exceptions and when they are raised −

Collection Exception	Raised in Situations
COLLECTION_IS_NULL	You try to operate on an atomically null collection.
NO_DATA_FOUND	A subscript designates an element that was deleted, or a nonexistent element of an associative array.
SUBSCRIPT_BEYOND_COUNT	A subscript exceeds the number of elements in a collection.
SUBSCRIPT_OUTSIDE_LIMIT	A subscript is outside the allowed range.
VALUE_ERROR	A subscript is null or not convertible to the key type. This exception might occur if the key is defined as a PLS_INTEGER range, and the subscript is outside this range.

For more tutorials visit our Oracle PL/SQL Blog.

Number of rows affected by an UPDATE in PL/SQL

 

The following query can be used to know how many rows are updated. 

SQL%rowcount is used to find the number rows updated.

DECLARE 

    i NUMBER; 

BEGIN 

    UPDATE emp

    SET ename = 'SCOTT' 

    WHERE  empno =5577; 

    i := SQL%rowcount; 

    --note that assignment has to precede COMMIT

    COMMIT; 

    dbms_output.Put_line(i); 

END; 

For more tutorials visit our Oracle PL/SQL Blog.

Oracle Purchasing Approval Hierarchies

Oracle Purchasing Approval Hierarchies

 

Purchasing setup of approval hierarchies: There are two most commonly known methods to route documents for approval.

1. Approval Hierarchies (uses position hierarchies)
2. Employee/Supervisor Relationships (use employee/supervisor relationship)

* Third method of Advanced Approval Support for Requisitions (Release 12 uses integration with Oracle Approvals Management) . However, in this article, the focus here is set on the above two most commonly used methods.

1. Position Hierarchies: Position Hierarchies are hierarchies that have a position relationship. Purchasing utilizes positions as a roadmap to determine how and where documents will be routed once the approval process has been initiated. It is first necessary to have created all positions that are going to be used in the system.

Once all positions have been created, it is necessary to build the position hierarchy. Each position has approval limits, so when a purchase order exceeds the limits of the position, the purchase order is forwarded onto the next position in the Hierarchy. The hierarchy for positions is defined in the Position Hierarchy form.

When this is complete or is changed, the Fill Employee Hierarchy concurrent program must be run for the new hierarchy to come into effect. You must set up Positions if you plan to use either security or approval hierarchies. If you are using Shared HR navigate, Purchasing: Setup: Personnel: Position Hierarchy. Otherwise, if you are using a full install of HR then navigate Human Resources: Work Structures: Position: Hierarchy.

2. Employee/Supervisor Relationships: This type of hierarchy does not use the Approval Hierarchy form, but is defined by the employee/supervisor relationship. The supervisor of an employee is defined on the Assignment region of the Employee form. If the purchase order entered by the employee exceeds the approval limits, the purchase order is forwarded to the employees' supervisor, as defined on the Employee form.

To implement this form of approval routing, you need only to define jobs. The job will then serve as the tie to the Approval group, and based on the approval limits from the Approval Group, the Document will either be Approved or Forwarded to the Employees’ Supervisor.

If no Supervisor is able to be located and the job assigned to the employee does not have Approval Authority, then the Approving employee must enter a Forward-to person, or the Document will be returned to an Incomplete status and a notification will be sent to the Approving employee, stating - 'No Approver Found - Please Select a Forward-To Employee'.

Pl-Sql: Null Values in Comparisons and Conditional Statements... Errors

 Pl-Sql: Null Values in Comparisons and Conditional Statements... Errors

Pl-Sql: Null Values in Comparisons and Conditional Statements...

When working with nulls, you can avoid some common mistakes by keeping in mind the following rules:

1. Comparisons involving nulls always yield NULL
2. Applying the logical operator NOT to null yields NULL
3. In conditional control statements, if the condition yields NULL, its associated sequence of statements is not executed
4. If the expression in a simple CASE statement or CASE expression yields NULL, it cannot be matched by using WHEN NULL. In this case, you would need to use the searched case syntax and test WHEN expression IS NULL.

In the example below, you might expect the sequence of statements to execute because x and y seem unequal. But, nulls are indeterminate. Whether or not x is equal to y is unknown. Therefore, the IF condition yields NULL and the sequence of statements is bypassed.

DECLARE
x NUMBER := 5;
y NUMBER := NULL;
BEGIN
IF x != y THEN -- yields NULL, not TRUE
dbms_output.put_line('x != y'); -- not executed
ELSIF x = y THEN -- also yields NULL
dbms_output.put_line('x = y');
ELSE
dbms_output.put_line('Can''t tell if x and y are equal or not...');
END IF;
END;
/
In the next example, you might expect the sequence of statements to execute because a and b seem equal. But, again, that is unknown, so the IF condition yields NULL and the sequence of statements is bypassed.

DECLARE
a NUMBER := NULL;
b NUMBER := NULL;
BEGIN
IF a = b THEN -- yields NULL, not TRUE
dbms_output.put_line('a = b'); -- not executed
ELSIF a != b THEN -- yields NULL, not TRUE
dbms_output.put_line('a != b'); -- not executed
ELSE
dbms_output.put_line('Can''t tell if two NULLs are equal');
END IF;
END;
/
NULLs and the NOT Operator
Recall that applying the logical operator NOT to a null yields NULL. Thus, the following two statements are not always equivalent:

IF x > y THEN | IF NOT x > y THEN
high := x; | high := y;
ELSE | ELSE
high := y; | high := x;
END IF; | END IF;

The sequence of statements in the ELSE clause is executed when the IF condition yields FALSE or NULL. If neither x nor y is null, both IF statements assign the same value to high. However, if either x or y is null, the first IF statement assigns the value of y to high, but the second IF statement assigns the value of x to high.


NULLs and Zero-Length Strings

PL/SQL treats any zero-length string like a null. This includes values returned by character functions and Boolean expressions. For example, the following statements assign nulls to the target variables:

DECLARE
null_string VARCHAR2(80) := TO_CHAR('');
address VARCHAR2(80);
zip_code VARCHAR2(80) := SUBSTR(address, 25, 0);
name VARCHAR2(80);
valid BOOLEAN := (name != '');
BEGIN
NULL;
END;
/
Use the IS NULL operator to test for null strings, as follows:

IF my_string IS NULL THEN ...

NULLs and the Concatenation Operator

The concatenation operator ignores null operands. For example, the expression

'apple' || NULL || NULL || 'sauce'

returns the following value:

'applesauce'

NULLs as Arguments to Built-In Functions

If a null argument is passed to a built-in function, a null is returned except in the following cases.

The function DECODE compares its first argument to one or more search expressions, which are paired with result expressions. Any search or result expression can be null. If a search is successful, the corresponding result is returned. In the following example, if the column rating is null, DECODE returns the value 1000:

DECLARE
the_manager VARCHAR2(40);
name employees.last_name%TYPE;
BEGIN
-- NULL is a valid argument to DECODE. In this case, manager_id is null
-- and the DECODE function returns 'nobody'.
SELECT DECODE(manager_id, NULL, 'nobody', 'somebody'), last_name
INTO the_manager, name FROM employees WHERE employee_id = 100;
dbms_output.put_line(name || ' is managed by ' || the_manager);
END;
/
The function NVL returns the value of its second argument if its first argument is null. In the following example, if the column specified in the query is null, the function returns the value -1 to signify a non-existent employee in the output:

DECLARE
the_manager employees.manager_id%TYPE;
name employees.last_name%TYPE;
BEGIN
-- NULL is a valid argument to NVL. In this case, manager_id is null
-- and the NVL function returns -1.
SELECT NVL(manager_id, -1), last_name
INTO the_manager, name FROM employees WHERE employee_id = 100;
dbms_output.put_line(name || ' is managed by employee #' || the_manager);
END;
/
The function REPLACE returns the value of its first argument if its second argument is null, whether the optional third argument is present or not. For example, the following call to REPLACE does not make any change to the value of OLD_STRING:

DECLARE
string_type VARCHAR2(60);
old_string string_type%TYPE := 'Apples and oranges';
my_string string_type%TYPE := 'more apples';
-- NULL is a valid argument to REPLACE, but does not match
-- anything so no replacement is done.
new_string string_type%TYPE := REPLACE(old_string, NULL, my_string);
BEGIN
dbms_output.put_line('Old string = ' || old_string);
dbms_output.put_line('New string = ' || new_string);
END;
/
If its third argument is null, REPLACE returns its first argument with every occurrence of its second argument removed. For example, the following call to REPLACE removes all the dashes from DASHED_STRING, instead of changing them to another character:

DECLARE
string_type VARCHAR2(60);
dashed string_type%TYPE := 'Gold-i-locks';
-- When the substitution text for REPLACE is NULL,
-- the text being replaced is deleted.
name string_type%TYPE := REPLACE(dashed, '-', NULL);
BEGIN
dbms_output.put_line('Dashed name = ' || dashed);
dbms_output.put_line('Dashes removed = ' || name);
END;
/
If its second and third arguments are null, REPLACE just returns its first argument.
Posted by Sairamgoud at 3:05 PM 0 comments
PL/SQL -Advantages
Advantages of PL/SQL

PL/SQL is a completely portable, high-performance transaction processing language that offers the following advantages:

Support for SQL
Support for object-oriented programming
Better performance
Higher productivity
Full portability
Tight integration with Oracle
Tight security
Tight Integration with SQL

The PL/SQL language is tightly integrated with SQL. You do not have to translate between SQL and PL/SQL datatypes: a NUMBER or VARCHAR2 column in the database is stored in a NUMBER or VARCHAR2 variable in PL/SQL. This integration saves you both learning time and processing time. Special PL/SQL language features let you work with table columns and rows without specifying the datatypes, saving on maintenance work when the table definitions change.

Running a SQL query and processing the result set is as easy in PL/SQL as opening a text file and processing each line in popular scripting languages.

Using PL/SQL to access metadata about database objects and handle database error conditions, you can write utility programs for database administration that are reliable and produce readable output about the success of each operation.

Many database features, such as triggers and object types, make use of PL/SQL. You can write the bodies of triggers and methods for object types in PL/SQL.

Support for SQL
SQL has become the standard database language because it is flexible, powerful, and easy to learn. A few English-like commands such as SELECT, INSERT, UPDATE, and DELETE make it easy to manipulate the data stored in a relational database.

PL/SQL lets you use all the SQL data manipulation, cursor control, and transaction control commands, as well as all the SQL functions, operators, and pseudocolumns. This extensive SQL support lets you manipulate Oracle data flexibly and safely. Also, PL/SQL fully supports SQL datatypes, reducing the need to convert data passed between your applications and the database.

PL/SQL also supports dynamic SQL, a programming technique that makes your applications more flexible and versatile. Your programs can build and process SQL data definition, data control, and session control statements at run time, without knowing details such as table names and WHERE clauses in advance.

Better Performance
Without PL/SQL, Oracle must process SQL statements one at a time. Programs that issue many SQL statements require multiple calls to the database, resulting in significant network and performance overhead.

With PL/SQL, an entire block of statements can be sent to Oracle at one time. This can drastically reduce network traffic between the database and an application. PL/SQL even has language features to further speed up SQL statements that are issued inside a loop.

PL/SQL stored procedures are compiled once and stored in executable form, so procedure calls are efficient. Because stored procedures execute in the database server, a single call over the network can start a large job. This division of work reduces network traffic and improves response times. Stored procedures are cached and shared among users, which lowers memory requirements and invocation overhead.

Higher Productivity

PL/SQL extends tools such as Oracle Forms and Oracle Reports. With PL/SQL in these tools, you can use familiar language constructs to build applications. For example, you can use an entire PL/SQL block in an Oracle Forms trigger, instead of multiple trigger steps, macros, or user exits.

PL/SQL is the same in all environments. Once you learn PL/SQL with one Oracle tool, you can transfer your knowledge to other tools.

Full Portability

Applications written in PL/SQL can run on any operating system and platform where the Oracle database runs. With PL/SQL, you can write portable program libraries and reuse them in different environments.

Tight Security

PL/SQL stored procedures move application code from the client to the server, where you can protect it from tampering, hide the internal details, and restrict who has access. For example, you can grant users access to a procedure that updates a table, but not grant them access to the table itself or to the text of the UPDATE statement.

Triggers written in PL/SQL can control or record changes to data, making sure that all changes obey your business rules.

Support for Object-Oriented Programming

Object types are an ideal object-oriented modeling tool, which you can use to reduce the cost and time required to build complex applications. Besides allowing you to create software components that are modular, maintainable, and reusable, object types allow different teams of programmers to develop software components concurrently.

By encapsulating operations with data, object types let you move data-maintenance code out of SQL scripts and PL/SQL blocks into methods. Also, object types hide implementation details, so that you can change the details without affecting client programs.

In addition, object types allow for realistic data modeling. Complex real-world entities and relationships map directly into object types. This direct mapping helps your programs better reflect the world they are trying to simulate.

For more tutorials visit our Oracle PL/SQL Blog.

Query to retrieve KFF's in Oracle E-Business Suite

 Query to retrieve KFF's in Oracle E-Business Suite

Query to retrieve KFF's in Oracle E-Business Suite

SELECT COUNT (*), fat.application_name

FROM fnd_id_flexs fif, fnd_application_tl fat

WHERE fat.application_id = fif.application_id

AND fat.LANGUAGE = 'US'

GROUP BY fat.application_name

ORDER BY fat.application_name

SELECT a.application_short_name, fat.application_name, fif.id_flex_code,

fif.id_flex_name

FROM fnd_id_flexs fif, fnd_application fa, fnd_application_tl fat

WHERE fa.application_id = fif.application_id

AND fat.application_id = fa.application_id

AND fat.LANGUAGE = 'US'ORDER BY fat.application_name, fif.id_flex_name