A variable, by definition, is a name given to a memory space.
In Oracle PLSQL a variable allows a programmer to store the needed data / values in variables while the program is being executed.
The Syntax for declaring a variable in Oracle PLSQL is:
variable_name [CONSTANT] data_type [NOT NULL] [:= DEFAULT initial value]
For example we can create a variable named ‘websitename’ in Oracle PLSQL as:
websitename VARCHAR2(100);
In the above statement we have just created a variable but the variable doesn’t have anything stored in it. We can assign a value to the above created ‘websitename’ variable as:
websitename := 'Website Name Is techhoney.com';
We can merge the two steps above and can create a variable along with assigning some value to it in a single statement as:
websitename VARCHAR2(100) := 'Website Name Is techhoney.com';
Later we can change the value of ‘websitename’ variable to something else e.g.
websitename := 'This is just a test';
Here we should understand that we have created a variable and not a constant; in case of constant the value assigned to it cannot be changed.
Below is an example is to create a constant in Oracle PLSQL:
grandTotal CONSTANT NUMERIC(10,1) := 123.456;
Note: Once assigned, the value of a constant cannot be changed.