create table employees
( empno number(4) constraint e_pk primary key
constraint e_empno_chk check (empno > 7000)
, ename varchar2(8) constraint e_name_nn not null
, init varchar2(5) constraint e_init_nn not null
, job varchar2(8)
, mgr number(4) constraint e_mgr_fk references employees
, bdate date constraint e_bdat_nn not null
, msal number(6,2) constraint e_msal_nn not null
, comm number(6,2)
, deptno number(2) default 10
, constraint e_sales_chk check
(decode(job,'salesrep',0,1)
+ nvl2(comm, 1,0) = 1)
) ;
create table departments
( deptno number(2) constraint d_pk primary key
constraint d_deptno_chk check (mod(deptno,10) = 0)
, dname varchar2(10) constraint d_dname_nn not null
constraint d_dname_un unique
constraint d_dname_chk check (dname = upper(dname))
, location varchar2(8) constraint d_loc_nn not null
constraint d_loc_chk check (location = upper(location))
, mgr number(4) constraint d_mgr_fk references employees
) ;
alter table employees add
(constraint e_dept_fk foreign key (deptno) references departments);
listing 7-8. the salgrades table
create table salgrades
( grade number(2) constraint s_pk primary key
, lowerlimit number(6,2) constraint s_lower_nn not null
constraint s_lower_chk check (lowerlimit >= 0)
, upperlimit number(6,2) constraint s_upper_nn not null
, bonus number(6,2) constraint s_bonus_nn not null
, constraint s_lo_up_chk check
(lowerlimit <= upperlimit)
) ;
alter table employees add
(constraint e_dept_fk foreign key (deptno) references departments);
listing 7-8. the salgrades table
create table salgrades
( grade number(2) constraint s_pk primary key
, lowerlimit number(6,2) constraint s_lower_nn not null
constraint s_lower_chk check (lowerlimit >= 0)
, upperlimit number(6,2) constraint s_upper_nn not null
, bonus number(6,2) constraint s_bonus_nn not null
, constraint s_lo_up_chk check
(lowerlimit <= upperlimit)
) ;
create table offerings
( course varchar2(6) constraint o_course_nn not null
constraint o_course_fk references courses
, begindate date constraint o_begin_nn not null
, trainer number(4) constraint o_train_fk references employees
, location varchar2(8)
, constraint o_pk primary key
(course,begindate)
) ;
create table registrations
( attendee number(4) constraint r_att_nn not null
constraint r_att_fk references employees
, course varchar2(6) constraint r_course_nn not null
, begindate date constraint r_begin_nn not null
, evaluation number(1) constraint r_eval_chk check (evaluation in (1,2,3,4,5))
, constraint r_pk primary key
(attendee,course,begindate)
, constraint r_off_fk foreign key (course,begindate)
references offerings
) ;
create table history
( empno number(4) constraint h_empno_nn not null
constraint h_empno_fk references employees
on delete cascade
, beginyear number(4) constraint h_byear_nn not null
, begindate date constraint h_bdate_nn not null
, enddate date
, deptno number(2) constraint h_dept_nn not null
constraint h_dept_fk references departments
, msal number(6,2) constraint h_msal_nn not null
, comments varchar2(60)
, constraint h_pk primary key (empno,begindate)
, constraint h_beg_end check (begindate < enddate)
) ;
函式呼叫棧比較有意思
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函式呼叫棧比較有意思
昨天和海洋一塊研究了下函式呼叫棧，順便寫兩句。不足或錯誤之處請包涵！理解呼叫棧最重要的兩點是 棧的結構，ebp暫存器的作用。首先要認識到這樣兩個事實 2 幾乎所有本地編譯器都會在每個函式體之前插入類似如下指令 push ebp mov ebp esp 棧底方向，高位位址 引數3 引數2 引數1 返回...