Oracle SQL （2）：SQL Fundamentals(Day II)

联合查询：

1.等值连接:（内连接，自然连接）

SQL> select d.deptno, d.dname, e.empno, e.ename, e.sal
  2  from dept d, emp e
  3  where d.deptno=e.deptno;

13 rows selected.

2.非等值连接:

SQL> select e.ename, e.sal, s.grade
  2  from emp e, salgrade s
  3* where e.sal between s.losal and s.hisal

3.自连接:

SQL> select e.ename, m.ename
  2  from emp e, emp m
  3  where e.mgr=m.empno;

4.外连接:

sql99(sql2003) standard:

SQL> select e.empno, e.ename, d.dname
  2  from emp e left outer join dept d
  3  on e.deptno = d.deptno;

14 rows selected.

oracle standard:

SQL> select e.empno, e.ename, d.dname
  2  from emp e, dept d
  3  where e.deptno=d.deptno(+); 

14 rows selected.

oracle can't but sql99 can:

SQL> select e.empno, e.ename, d.dname
  2  from emp e full outer join dept d
  3  on e.deptno=d.deptno;

15 rows selected.

5.笛卡尔乘积：

SQL> select d.deptno, d.dname, e.empno, e.ename, e.sal
  2  from dept d, emp e

56 rows selected.(14 * 4)

子查询:

SQL> select empno, ename, sal        
  2  from emp
  3  where sal > (select sal                     
  4               from emp
  5               where ename='BLAKE');

null值处理：

SQL> select empno, ename, sal
  2  from emp
  3  where empno not in (select mgr
  4                      from emp);

no rows selected. (And results to now result).

SQL> select empno, ename, sal
  2  from emp
  3  where empno in (select mgr
  4                  from emp);

EMPNO ENAME    SAL
----- ------ -----
 7566 JONES   2975
 7698 BLAKE   2850
 7782 CLARK   2450
 7788 SCOTT   3000
 7839 KING    5000
 7902 FORD    3000

6 rows selected. (Or results to records).

SQL> select empno, ename, sal
  2  from emp
  3* where empno not in (select mgr
                         from emp
                         where mgr is not null)

EMPNO ENAME    SAL
----- ------ -----
 7369 SMITH    800
 7499 ALLEN   1600
 7521 WARD    1250
 7654 MARTIN  1250
 7844 TURNER  1500
 7876 ADAMS   1100
 7900 JAMES    950
 7934 MILLER  1300

8 rows selected. (Remove null value results to records).

Top N分析：

SQL> select * from (select empno, ename, sal from emp order by sal desc) where rownum < 4 order by rownum;

EMPNO ENAME    SAL
----- ------ -----
 7839 KING    5000
 7788 SCOTT   3000
 7902 FORD    3000

Union/Union All/Intersect/Minus：

SQL> break on deptno skip 1;

SQL> select deptno, job, sum(sal)
  2  from emp
  3  group by deptno, job
  4  union
  5  select deptno, to_char(null), sum(sal)
  6  from emp
  7  group by deptno
  8  union
  9  select to_number(null), to_char(null), sum(sal)
 10  from emp;

SQL> select deptno, job, sum(sal) tsal
  2  from emp
  3  group by rollup(deptno,job);

Insert/Update:

SQL> create table test as
  2  select empno, ename, sal
  3  from emp   
  4  where 1=2;

SQL> insert into test values(100, 'tom', null);
SQL> insert into test(empno, ename) values (101, 'mike');

SQL> truncate table test;
SQL> insert into test select empno, ename, sal from emp;
14 rows created.

SQL> show feedback;
FEEDBACK ON for 6 or more rows
SQL> set feedback off;
SQL> set feedback on;
SQL> set feedback 6;

SQL> update test set sal = (select sal from emp where empno=7499) where empno=7369;

Truncate/Delete:

DML(Insert, Update, Delete, Merge)
DDL(Create, Alter, Drop, Rename, Truncate, Comment)
DCL(Grant, Revoke)
Transaction Control(Commit, Rollback, Savepoint)

显示提交：rollback, commit
隐式提交：DDL/DCL,正常退出
          begin
              commit;
              DDL/DCL;
              commit;
          end
隐式回滚：异常退出

SQL> savepoint A;
Savepoint created.

SQL> delete from test where empno=7369;
1 row deleted.

SQL> rollback to savepoint A;

Create Table, View, Sequence, Index, Synonyms(同义词)

varchar2(10)/varchar2(10 char)
number/number(8, 2)
CLOB(text)/BLOB(Binary, media, exe)
BFile: Binary data stored in an external file

Constraint:
not null, unique, primary key, foreign key,check

SQL> purge recyclebin;

SQL> drop table test purge;

Table:

SQL> create table test(id number, name varchar2(10), create_date date default sysdate);
SQL> insert into test values(100, 'mike', default);

SQL> create table et(eno number,
  2                  ename varchar2(10),
  3                  constraint en_u_eno unique(eno));

SQL> create table dt(dno number(4) primary key,
  2                  dname varchar2(10));

SQL> create table d as select deptno dno, dname, loc from dept;    
SQL> create table e as select empno, ename, sal, deptno as dno from emp;

SQL> alter table d add constraint d_pk primary key (dno);
SQL> alter table e add constraint e_fk foreign key (dno) references d(dno);

SQL> drop table e purge;

SQL> create table e(eno number,
  2                 ename varchar2(10),
  3                 dno number references d(dno) on delete set null);

SQL> create table e1(eno number,
  2                  ename varchar2(10),
  3                  dno number references d(dno) on delete cascade);

SQL> alter table e1 read only;

SQL> create table e2 as select * from emp;
SQL> alter table e2 add constraint ck_e2 check ((sal > 0) and (sal < 10000));

View:

SQL> conn / as sysdba;
SQL> grant create view to scott;

SQL> conn scott/tiger;

SQL> create or replace view v1 as select empno, ename, sal from emp with check option;
SQL> create or replace view v2 as select empno, ename, sal from emp with read only;

Index:

{TODO:}

Sequence:

{TODO:}

Synonym:

SQL> conn / as sysdba;
SQL> grant create synonym to scott;

SQL> conn scott/tiger;
SQL> create synonym sg for salgrade;