PL/SQL 11g R2 —— 定义PL/SQL变量 ！

identifier [constant] datatype [not null] [:= | default expr];
v_ename varchar2(10);
v_sal number(6,2);
v_tax constant number(3,2) := 5.5;
v_data data;v_b boolean not null default false;

SQL> set serveroutput on
SQL> declare
2    v_myname varchar2(20);
3  begin
4    dbms_output.put_line('My name is :' || v_myname);
5    v_myname := 'zhangshenghong';
6    dbms_output.put_line('My name is :' || v_myname);
7  end;
8  /
My name is :
My name is :zhangshenghong

PL/SQL 过程已成功完成。

SQL> set serveroutput on
SQL> declare
2    v_myname varchar2(20) default 'zhangqu';
3  begin
4    v_myname := 'zhangshenghong';
5    dbms_output.put_line('My name is :' || v_myname);
6  end;
7  /
My name is :zhangshenghong

PL/SQL 过程已成功完成。

SQL> set serveroutput on
SQL> declare
2    v_event varchar2(20) := 'Wather''s day';
3  begin
4    dbms_output.put_line(v_event);
5    v_event := q'!Father's day!';
6    dbms_output.put_line(v_event);
7    v_event := q'[Monther's day]';
8    dbms_output.put_line(v_event);
9  end;
10  /
Wather's day
Father's day
Monther's day

PL/SQL 过程已成功完成。

SQL> set serveroutput on
SQL> variable b_salary number;
SQL> begin
2    select salary into :b_salary from employees where employee_id = 178;
3  end;
4  /

PL/SQL 过程已成功完成。

SQL> print b_salary;

B_SALARY
----------
7000

SQL> select first_name,last_name from employees where salary = :b_salary;

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