PL/SQL LEARNING NOTES(1)

1.About PL/SQL
   Stands for "Procedural Language extension to SQL"
 Is Oracle Corporation's standard data access language for relational databases
 Prodides a block structure for executable units of code
2.PL/SQL Block Structure
 DECLARE(Optional)
    -Variables,cursors,User-defined exceptions
 BEGIN(mandatory)
    -SQL statements
    -PL/SQL statements
 EXCEPTION(Optional)
    -Actions to perform when errors occur
 END
3.Block Types
 Anonymous
 Procedure
    -Procedure name IS
 Function
    -Function name RETURN datatype is
4.Execute an Anonymous Block(first set serverout on)
  1 declare
  2  v_fname varchar2(20);
  3  begin
  4     select first_name into v_fname from employees where employee_id=100;
  5     dbms_output.put_line('The result is ' || v_fname);
  6  end;
  7  /
5.Declaring an initializing PL/SQL Variables
   syntax:identifier [constant] datatype [NOT NULL] [:= | DEFAULT expr];
6.Types of Variables
  PL/SQL variables
   -Scalar
   -Composite
   -Reference
  Non-PL/SQL variables:Blind variables
   -Large object(LOB)
7.Base Scalar Data Types
   -CHAR
   -VARCHAR2
   -NUMBER
   -BINARY_INTEGER
   -PLS_INTEGER
   -BOOLEAN
   -BINARY_FLOAT
   -BINARY_DOUBLE
8.%TYPE Attribute
    -A database column definition
    -Another declare variable
  Syntax
    -identifier table.column_name%TYPE
  Examples
    -emp_lname employee.last_name%TYPE
9.Printing Blind variables
   SQL> variable b_emp_salary number
   SQL> variable b_emp_salary number
   SQL> begin
        2  select salary into :b_emp_salary
        3  from employees where employee_id=178;
        4  end;
        5  /
   PL/SQL procedure successfully completed.

   SQL> print b_emp_salary

   B_EMP_SALARY
   ------------
           7000
   select first_name, last_name from employees
     2  where salary=:b_emp_salary;

  FIRST_NAME           LAST_NAME
  -------------------- -------------------------
  Oliver               Tuvault
  Sarath               Sewall
  Kimberely            Grant