PL/SQL Exceptions

An error that occurs during execution of the program is called exception, Like other programming languages, PL/SQL offers a way to catch these exceptions and handle them.

There are two types of exceptions in PL/SQL

1. System-Defined Exceptions 
2. User-Defined Exceptions 

PL/SQL For Loop

PL/SQL FOR loop is used when we need to execute set of statements for the specific number of times and loop operates between the start and end counter values. The counter is always incremented by one and once the counter reaches to end integer value, the loop terminates

The syntax of PL/SQL FOR Loop is like this

FOR counter_variable IN start value.. end value LOOP

statements to execute 

END LOOP;

PL/SQL CASE Statement, Decision Making Statement in PL/SQL

Like real life in programming sometimes we need to execute some code on a specific condition, PL/SQL CASE statement allows us to execute a sequence of instructions based on a selector (A variable, function, expression etc)
and if selector value is equal to value or expression in WHEN clause then corresponding THEN clause will execute and process the statements

PL/SQL Variables and Constants

A variable in any programming language is the name of space where values are stored and controlled by our code/program

• We can not use reserve keyword as a variable name 
• Variable length should not exceed 30 characters
• The variable name consists of letters followed by other letters, dollar sign, underscore and numerals
• The variable name should be clear and easy to understand

Here we'll learn how to declare and initialize variables in PL/SQL

The basic syntax for declaring a variable in PL/SQL is following

variable_name [CONSTANT] datatype [NOT NULL] [:= | DEFAULT initial_value] 

Here variable_name is the identifier of variable and datatype is a valid PL/SQL datatype. CONSTANT and DEFAULT are keywords used to define constants and set default values of variables