Sub-program (procedure and function) in SQL

What is sub-program in SQL?
Sub-program is a programming unit which is created in a database to perform some tasks on data.

Basic usages of sub-program?
Create
CREATE PROCEDURE or CREATE FUNCTION

Delete
DROP PROCEDURE or DROP FUNCTION

Two kinds of sub-program:
PROCEDURE: perform an action but NOT return a value, but we can get output value by OUT variables.
and FUNCTION: compute and return a value

Create procedure:

CREATE [OR REPLACE] PROCEDURE procedure_name
[(parameter_name [IN | OUT | IN OUT] type [, ...])]
{IS | AS}
BEGIN
  < procedure_body >
END procedure_name;

Create function:

CREATE [OR REPLACE] FUNCTION function_name
[(parameter_name [IN | OUT | IN OUT] type [, ...])]
RETURN return_datatype
{IS | AS}
BEGIN
   < function_body >
END [function_name];

What is cursor?
A cursor holds the rows (one or more) returned by a SQL statement.

Triggers are stored programs, which are automatically executed or fired when some events occur.

CREATE [OR REPLACE ] TRIGGER trigger_name 
{BEFORE | AFTER | INSTEAD OF } 
{INSERT [OR] | UPDATE [OR] | DELETE} 
[OF col_name] 
ON table_name 
[REFERENCING OLD AS o NEW AS n] 
[FOR EACH ROW] 
WHEN (condition)  
DECLARE
   Declaration-statements
BEGIN 
   Executable-statements
EXCEPTION
   Exception-handling-statements
END;

A database transaction is an atomic unit of work that may consist of one or more related SQL statements.

Crystal report in MySQL (current version Crystal report 2013). It is a business intelligence tool to provide report from a data source.