Introduction to PL/SQL

PL/SQL is procedural programming language that uses sequencial instructions to process data.  SQL commands can be used withing PL/SQL to intract with the database.  PL/SQL is also part of the Oracle development enviroment which can be stored directly into an Oracle database.   The syntax to create PL/SQL is as follows:
DECLARE
  declare here all the varibales
BEGIN
  write here all the program statements
EXCEPTION
  write here all the error-handling statements
END;
Variables are declared in the program declaration section using PL/SQL variables types, which are similar to SQL variables types.  All the program statements are defined in the BEGIN section of the program and EXCEPTION section is for error handling statements.
The following are list of PL/SQL variable types that are also SQL variable types:

Variable type	Description	Example
VARCHAR2	Variable-lenth character strings	name VARCHAR2(35);
CHAR	Fixed-lenth character string	middle_init VARCHAR2(1);
DATE	Date type	birth_date DATE;
NUMBER	Floating, fixed, or integer numbers	price NUMBER(4);
LONG	Long text up to 32760 bytes	comment LONG;
BINARY_INTEGER	Integer number	counter BINARY_INTEGER;
INTEGER	Integer number	counter INTEGER;
INT	Integer number	counter INT;
SMALLINT	Integer number	counter SMAILLINT;
DEC	Floating point number	price DEC;
DECIMAL	Floating point number	price DECIMAL;
DOUBLE	Floating point number	price DOUBLE;
PRECISION	Floating point number	price PRECISION;
NUMERIC	Floating point number	price NUMERIC;
REAL	Floating point number	price REAL;
BOOLEAN	True or false	Is_customer BOOLEAN;
LOB	large objects	product_image LOB;

The following is simple PL/SQL program that calculates some one's age:

DECLARE    name VARCHAR2(35);    birth_date DATE;   current_date DATE;   age NUMBER(2); BEGIN   name := 'Joe doe';    birth_date := TO_DATE('05/01/1980','MM/DD/YYYY');   current_date := SYSDATE;   age := TRUNC((current_date - birth_date)/365.25, 0);   DBMS_OUTPUT.PUT_LINE('Name: '||name ||' Age: '|| age); END; /

:= is an assignment sign for PL/SQL and = is comparison sign.   TO_DATE is a function that converts character string to internal date format [see variable types for more conversion functions] and TRUNC is another function that truncates the result to specified precision points.  Date subtracted date will give you number of days, 365.25 is divided by to convert days into years.  DBMS_OUTPUT.PUT_LINE() displays the program output whether it's strings or variables.  SYSDATE is current system date.

Bellow is picture of this example on sql plus server:
Before you insert PL/SQL code into SQL Server, you have to set up the server output which is the space to display code result.  Type this command before inserting the code; SET SERVEROUTPUT ON SIZE 4000.