Variables and constants in pl/sql, PL-SQL Programming

Variables and Constants in PL/SQL

The PL/SQL permits you to declare constants and variables, and then use them in SQL and procedural statements anywhere in the expression. Though, forward references are not permitted. So, you should declare a constant or variable before referencing it in another statement, involving other declarative statements.

Declaring Variables

The Variables can have any SQL datatype, like CHAR, DATE, or NUMBER, or any PL/SQL datatype, like BOOLEAN or BINARY_INTEGER. For e.g., suppose that you want to declare a variable name part_no         to hold 4-digit numbers and a variable name in_stock    to hold the Boolean value TRUE or FALSE. You can declare these variables as shown:

part_noNUMBER(4);

in_stock BOOLEAN;

You can also declare nested tables, records using the TABLE, VARRAY, variable-size arrays (varrays for short), and RECORD composite datatypes.

Assigning Values to a Variable

You can assign values to a variable in 2 ways. The first way uses the assignment operator (:=), a colon followed by an equal sign. You put the variable to the left of the operator and an expression to the right. Some examples are as follow:

tax := price * tax_rate;

bonus := current_salary * 0.10;

amount := TO_NUMBER(SUBSTR('750 dollars', 1, 3));

valid := FALSE;

The second way to assign values to a variable is to fetch or select database values into it. In the example below, you have Oracle calculate a 10% bonus when you select the salary of an employee:

SELECT sal * 0.10 INTO bonus FROM emp WHERE empno = emp_id;

After that, you can use the variable bonus in another calculation or insert its value into a database table.

Declaring Constants

Declaring a constant is such as declaring a variable except that you must add the keyword CONSTANT and right away assign a value to the constant. Subsequently, no more assignments to the constant are allowed. In the example below, you declare a constant named credit_limit:

credit_limit CONSTANT REAL := 5000.00;

Posted Date: 10/2/2012 1:13:13 AM | Location : United States







Related Discussions:- Variables and constants in pl/sql, Assignment Help, Ask Question on Variables and constants in pl/sql, Get Answer, Expert's Help, Variables and constants in pl/sql Discussions

Write discussion on Variables and constants in pl/sql
Your posts are moderated
Related Questions
Package STANDARD The package named STANDARD defines the PL/SQL atmosphere. The package specification globally declares the exceptions, types, and subprograms that are available

I would like to have a custom MS Access database designed and coded that would help me schedule my customer's orders and that would help me track my employees production output and

Keyword and Parameter Description: boolean_expression: This is an expression which results the Boolean value TRUE, FALSE, & NULL. It is related with a series of statement

Using %ROWTYPE The %ROWTYPE attribute gives a record type which represents a row in a table (or view). The record can store the whole row of data selected from the table or fetc

Updating Objects: To change the attributes of objects in an object table, you can use the UPDATE statement, as the illustration below shows: BEGIN UPDATE persons p SET p

WHILE-LOOP The WHILE-LOOP statement relates a condition with the series of statements enclosed by the keywords LOOP and END LOOP, as shown: WHILE condition LOOP sequence_of_sta

SQL Operators The PL/SQL uses all the SQL set, comparison, and row operators in the SQL statements. This part briefly describes some of these operators.  1. Comparison Opera

Delimiters A delimiter is a simple or compound symbol which has a special meaning to PL/SQL. For example, you use delimiters to symbolize an arithmetic operation like additio

I have a Pascal Source file that needs to be compiled into a Service. In addition, there are various functions (Pascal Procedures I guess) that need to be created to Read and Write

THEORY OF BIOGENESIS - This theory explains that the existing living organisms originated from pre-existing living beings not from non living entities. This concept of or