无名块：未命名的程序块

命名块：指过程，函数，包和触发器

定义部分：用于定义变量，常量，游标，触发器，复合数据类型

执行部分：用于实现应用模块功能，包含了要执行的PL/SQL语句和SQL语句

异常处理部分：用于处理执行部分可能出现的运行错误

[DECLARE

...  --定义部分]

BEGIN

...  --执行部分

[EXCEPTION

...  --异常处理部分]

END;

-------------------------------------

DECLARE

    a NUMBER;

BEGIN

    a:=1+2;

    DBMS_OUTPUT.PUT_LINE('1+2='||a);

EXCEPTION

    WHEN OTHERS THEN

        DBMS_OUTPUT.PUT_LINE('出现异常')

END;

/

条件分支语句：

DECLARE

    a1 number := 100;

    a2 number := 200;

BEGIN

    IF a1>a2 THEN

        DBMS_OUTPUT.PUT_LINE('a1 is larger than a2');

    ELSIF a1=a2 THEN

        DBMS_OUTPUT.PUT_LINE('a1 is equal to a2')

    ELSE

        DBMS_OUTPUT.PUT_LINE('a1 is smaller than a2');

    ENDIF;

END;

/

------------------------------------------------------------------------------------

DECLARE

    grade CHAR(1) := 'B';

    appraisal VARCHAR2(20);

BEGIN

    appraisal :=

    CASE grade

        WHEN 'A' THEN '优'

        WHEN 'B' THEN '良'

        WHEN 'C' THEN '中'

        WHEN 'D' THEN '及格'

        WHEN 'F' THEN '不及格'

    ELSE '没有这样的等级'

    DBMS_OUTPUT.PUT_LINE('Grade'||grade||'is'||appraisal);

END;

/

循环语句：

DECLARE

    total number := 0;

    salary number := 1800;

BEGIN

    LOOP

        total := total + salary;

        EXIT WHEN total > 2500

    END LOOP;

    DBMS_OUTPUT.PUT_LINE('total salary is'||total);

END;

/

----------------------------------------------------------------------------

DECLARE

    total number := 0;

    salary number := 1800;

BEGIN

    WHILE total<2500 LOOP

        total := total + salary;

    END LOOP;

    DBMS_OUTPUT.PUT_LINE('total salary is'||total);

END;

/

---------------------------------------------------------------------------

DELARE

    I INTEGER;

BEGIN

    FOR I IN REVERSE 1..3 LOOP

        DBMS_OUTPUT.PUT_LINE(I);

    END LOOP;

END;

/