細(xì)數(shù)你應(yīng)該修煉的Oracle基本功
http://database.51cto.com 2010-09-2608:56 yuexingtian Chinaunix
摘要：Oracle數(shù)據(jù)庫(kù)的基本功，主要涉及一些小算法，比如求部門(mén)中誰(shuí)的薪水最高，誰(shuí)是經(jīng)理等等。希望能滿足那些苦苦找尋正確解決方法的DBA們。
標(biāo)簽：Oracle
以下的文章，主要為大家在實(shí)際工作中提供一種解決方法。
---用戶名：scott
---密 碼：tiger
---*********Oracle表連接與子查詢示例************
---求部門(mén)中哪些人的薪水最高
select ename,sal from emp
join (select max(sal) max_sal, deptno from emp group by deptno) t
on (emp.sal = t.max_sal and emp.deptno = t.deptno);
---求部門(mén)平均薪水的等級(jí)
select deptno,avg_sal,grade from
(select deptno,avg(sal) avg_sal from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal);
---求部門(mén)平均的薪水等級(jí)
select deptno,avg(grade) from
(select deptno,ename,grade from emp join salgrade s on (emp.sal between s.losal and s.hisal)) t
group by deptno;
---雇員中哪些人是經(jīng)理人
select ename from emp where empno in (select distinct mgr from emp);
---不用組函數(shù)，求薪水的最高值
select sal from emp where sal not in
(select distinct e1.sal from emp e1 join emp e2 on (e1.sal < e2.sal))；
---用組函數(shù)，求薪水的最高值
select max(sal) from emp；
---求平均薪水最高的部門(mén)的部門(mén)編號(hào)
select deptno , avg_sal from
(select avg(sal) avg_sal,deptno from emp group by deptno) t
where avg_sal =
(select max(avg_sal) from (select avg(sal) avg_sal,deptno from emp group by deptno) t)；
----組函數(shù)嵌套的寫(xiě)法
select deptno , avg_sal from
(select avg(sal) avg_sal,deptno from emp group by deptno) t
where avg_sal =
(select max(avg(sal)) from emp group by deptno)；
---求平均薪水最高的部門(mén)的名稱(chēng)
select dname from dept
where deptno =
(
select deptno from
(select avg(sal) avg_sal,deptno from emp group by deptno) t
where avg_sal =
(select max(avg_sal) from (select avg(sal) avg_sal,deptno from emp group by deptno) t)
)；
---求部門(mén)平均薪水
1. select avg(sal) avg_sal,deptno from emp group by deptno
---求平均薪水的等級(jí)最低的部門(mén)的部門(mén)名稱(chēng)
select min(avg_sal) from
(
select avg(sal) avg_sal,deptno from emp group by deptno
)
--平均工資的最小值
select avg_sal,deptno from
(select avg(sal) avg_sal,deptno from emp group by deptno) t
where avg_sal =
(
select min(avg_sal) from
(
select avg(sal) avg_sal,deptno from emp group by deptno
)
)
--平均工資的最小值及部門(mén)編號(hào)
select t.avg_sal,t.deptno,s.grade from
(select avg(sal) avg_sal,deptno from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal)
where avg_sal =
(
select min(avg_sal) from
(
select avg(sal) avg_sal,deptno from emp group by deptno
)
)
--平均工資的最小值及部門(mén)編號(hào)和工資等級(jí)
select d.dname,t.avg_sal,t.deptno,s.grade from
(select avg(sal) avg_sal,deptno from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal)
join dept d on (t.deptno = d.deptno)
where avg_sal =
(
select min(avg_sal) from
(
select avg(sal) avg_sal,deptno from emp group by deptno
)
)
--平均工資的最小值及部門(mén)編號(hào)和工資等級(jí)及部門(mén)名稱(chēng)
----Another 按照題意的寫(xiě)法
select t1.deptno,t1.avg_sal,grade,d.dname from
(
select deptno,avg_sal,grade from
(select deptno,avg(sal) avg_sal from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal)
) t1
join dept d on (t1.deptno = d.deptno)
where grade =
(
select min(grade) from
(
select deptno,avg_sal,grade from
(select deptno,avg(sal) avg_sal from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal)
)
);
---創(chuàng)建視圖或者表，如果沒(méi)有權(quán)限
conn sys/sys as sysdba;
--已連接。
grant create table, create view to scott;
--授權(quán)成功。
---創(chuàng)建視圖
create view v$_dept_avg_sal_info as
select deptno,avg_sal,grade from
(select deptno,avg(sal) avg_sal from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal);
--視圖已建立。
---創(chuàng)建這個(gè)v$_dept_avg_sal_info視圖可以簡(jiǎn)化上面那個(gè)查詢的重復(fù)代碼
select t1.deptno,t1.avg_sal,grade,d.dname from
v$_dept_avg_sal_info t1
join dept d on (t1.deptno = d.deptno)
where grade =
(
select min(grade) from
v$_dept_avg_sal_info
);
---求比普通員工的最高薪水還要高的經(jīng)理的名稱(chēng)
select max(sal) from emp where empno not in
(select distinct mgr from emp where mgr is not null);
--普通員工的最高薪水
select ename from emp
where empno in (select distinct mgr from emp where mgr is not null)
and sal >
(
select max(sal) from emp where empno not in(select distinct mgr from emp where mgr is not null)
);
--普通員工的最高薪水還要高的經(jīng)理的名稱(chēng)
--- Oracle 聯(lián)機(jī)歸檔日志 備份方式
---求薪水最高的第6名到第10名雇員(rownum)
select ename,sal from
(select ename,sal,rownum r from
(
select ename, sal from emp order by sal desc
)
) where r>=6 and r<=10;
---五種約束條件
create table stu
(
id number(2),
name varchar2(20) constraint stu_name_nn not null,--非空約束
sex number(2),
age number(3),
sdate date,
grade number(3) default 1,
class number(3),
email varchar2(50),
constraint stu_name_email_uin unique(name,email)--唯一主鍵
) ;
insert into stu(name,email) values('','tianyuexing@163.com')
--ORA-01400: 無(wú)法將 NULL 插入 ("SCOTT"."STU"."NAME")
insert into stu(name,email) values('tianyuexing','tianyuexing@163.com');
insert into stu(name,email) values('tianyuexing','tianyuexing@163.com');
--ORA-00001: 違反唯一約束條件 (SCOTT.STU_NAME_EMAIL_UIN)
---PL/SQL 一個(gè)簡(jiǎn)單的存儲(chǔ)過(guò)程 分為四塊1.聲明declare2.begin 3.exception 4.end
set serveroutput on;
declare
v_num number :=0;
begin
v_num :=2/v_num;
dbms_output.put_line(v_num);
exception
when others then
dbms_output.put_line('error');
end;
---%type 變量聲明的好處。
declare
v_empno2 emp.empno%type;
begin
dbms_output.put_line('test');
end;
---Table 變量類(lèi)型
declare
type type_table_emp_empno is table of emp.empno%type index by binary_integer;
v_empnos type_table_emp_empno;
begin
v_empnos(0) := 2999;
v_empnos(1) := 2434;
v_empnos(-1) := 8989;
dbms_output.put_line(v_empnos(-1));
end;
---Record 變量類(lèi)型
declare
type type_record_dept is record
(
deptno dept.deptno%type,
dname dept.dname%type,
loc dept.loc%type
);
v_temp type_record_dept;
begin
v_temp.deptno := 20;
v_temp.dname := 'tianyuexing';
v_temp.loc := 'qhd';
dbms_output.put_line(v_temp.dname || ' ' ||v_temp.loc);
end;
---使用 %rowtype聲明record變量
declare
v_temp dept%rowtype;
begin
v_temp.deptno := 20;
v_temp.dname := 'yuexingtian';
v_temp.loc := 'qhd';
dbms_output.put_line(v_temp.dname || ' ' ||v_temp.loc);
end;
---SQL語(yǔ)句的運(yùn)用
declare
v_ename emp.ename%type;
v_sal emp.sal%type;
begin
select ename,sal into v_ename,v_sal from emp where empno = 7369;
dbms_output.put_line(v_ename ||' '||v_sal);
end;
declare
v_emp emp%rowtype;
begin
select * into v_emp from emp where empno = 7369;
dbms_output.put_line(v_emp.ename);
end;
--insert 語(yǔ)句
declare
v_deptno dept.deptno%type := 50;
v_dname dept.dname%type :='yuexingtian';
v_loc dept.loc%type := '秦皇島';
begin
insert into dept2 values (v_deptno,v_dname,v_loc);
commit;
end;
---sql%rowcount 多少條記錄被影響
declare
v_deptno emp2.deptno%type := 10;
v_count number;
begin
update emp2 set sal = sal/2 where deptno = v_deptno;
dbms_output.put_line(sql%rowcount ||'條記錄被影響');
end;
--create語(yǔ)句
begin
execute immediate 'create table T (nnn varchar2(20) default ''yuexingtian'')';
end;
---if語(yǔ)句，取出7369的薪水，如果<1200,則輸出'low',如果<2000則輸出'middle',否則輸出'high'.
declare
v_sal emp.sal%type;
begin
select sal into v_sal from emp
where empno = 7369;
if(v_sal < 1200) then
dbms_output.put_line('low');
elsif(v_sal < 2000) then
dbms_output.put_line('middle');
else
dbms_output.put_line('high');
end if;
end;
---循環(huán) loop (相當(dāng)于do while)
declare
i binary_integer := 1;
begin
loop
dbms_output.put_line(i);
i := i+1;
exit when (i>=11);
end loop;
end;
---when ……loop （相當(dāng)于while）
declare
j binary_integer := 1;
begin
while j<11 loop
dbms_output.put_line(j);
j := j+1;
end loop;
end;
---for ...in... loop
begin
for k in 1..10 loop
dbms_output.put_line(k);
end loop;
for k in reverse 1..10 loop --逆序
dbms_output.put_line(k);
end loop;
end;
--- 異常處理
declare
v_temp number(4);
begin
select empno into v_temp from emp where deptno = 10;
exception
when too_many_rows then --多條記錄的異常
dbms_output.put_line('記錄太多了');
when others then
dbms_output.put_line('error');
end;
declare
v_temp number(4);
begin
select empno into v_temp from emp where empno = 4444;
exception
when no_data_found then
dbms_output.put_line('沒(méi)有數(shù)據(jù)');
end;
---記錄數(shù)據(jù)庫(kù)錯(cuò)誤信息的errorlog
create table errorlog
(
id number primary key,
errcode number,
errmsg varchar2(1024),
errdate date
);
create sequence seq_errorlog_id start with 1 increment by 1; --創(chuàng)建遞增序列
--PL/SQL
declare
v_deptno dept.deptno%type :=10;
v_errcode number;
v_errmsg varchar2(1024);
begin
delete from dept where deptno = v_deptno;
commit;
exception
when others then
rollback;
v_errcode := SQLCODE;
v_errmsg := SQLERRM;
insert into errorlog values (seq_errorlog_id.nextval,v_errcode,v_errmsg,sysdate);
commit;
end;
select to_char(errdate,'YYYY-MM-DD HH24:MI:ss') from errorlog; ---具體的出錯(cuò)時(shí)間。
---游標(biāo)
declare
cursor c is
select * from emp;
v_emp c%rowtype;
begin
open c;
fetch c into v_emp;
dbms_output.put_line(v_emp.ename);
close c;
end;
---游標(biāo)，循環(huán)取出所有的記錄。
declare
cursor c is
select * from emp;
v_emp c%rowtype;
begin
open c;
loop
fetch c into v_emp;
exit when (c%notfound);
dbms_output.put_line(v_emp.ename);
end loop;
close c;
end;
---游標(biāo)while 循環(huán)
declare
cursor c is
select * from emp;
v_emp c%rowtype;
begin
open c;
fetch c into v_emp;
while (c%found) loop
dbms_output.put_line(v_emp.ename);
fetch c into v_emp;
end loop;
close c;
end;
---for循環(huán) 不用聲明變量，不用open游標(biāo) 不用close游標(biāo) 不用fetch
declare
cursor c is
select * from emp;
begin
for v_emp in c loop
dbms_output.put_line(v_emp.ename);
end loop;
end;
---帶參數(shù)的游標(biāo)
declare
cursor c(v_deptno emp.deptno%type, v_job emp.job%type)
is
select ename,sal from emp where deptno = v_deptno and job = v_job;
begin
for v_temp in c(30,'CLERK') loop
dbms_output.put_line(v_temp.ename);
end loop;
end;
---課更新的游標(biāo)
declare
cursor c
is
select * from emp2 for update;
begin
for v_temp in c loop
if (v_temp.sal < 2000) then
update emp2 set sal = sal * 2 where current of c;
elsif (v_temp.sal = 5000) then
delete from emp2 where current of c;
end if;
end loop;
commit;
end;
----創(chuàng)建存儲(chǔ)過(guò)程
create or replace procedure p
is
cursor c is
select * from emp2 for update;
begin
for v_emp in c loop
if (v_emp.deptno = 10) then
update emp2 set sal = sal + 10 where current of c;
elsif (v_emp.deptno = 20) then
update emp2 set sal = sal + 20 where current of c;
else
update emp2 set sal = sal + 50 where current of c;
end if;
end loop;
commit;
end;
---執(zhí)行存儲(chǔ)過(guò)程
exec p;
---或者
begin
p;
end;
---帶參數(shù)的存儲(chǔ)過(guò)程
create or replace procedure
max_num(v_a in number,v_b number,v_ret out number,v_temp in out number)
is
begin
if(v_a > v_b) then
v_ret := v_a;
else
v_ret := v_b;
end if;
v_temp := v_temp + 1;
end;
---調(diào)用這個(gè)存儲(chǔ)過(guò)程
declare
v_a number :=3;
v_b number :=4;
v_ret number;
v_temp number :=5;
begin
max_num(v_a, v_b, v_ret, v_temp);
dbms_output.put_line(v_ret);
dbms_output.put_line(v_temp);
end;
---函數(shù)
create or replace function
sal_tax(v_sal number)
return number
is
begin
if (v_sal < 2000) then
return 0.10;
elsif (v_sal < 2750) then
return 0.15;
else
return 0.20;
end if;
end;
--調(diào)用這個(gè)函數(shù)(別的函數(shù)怎么用，這個(gè)函數(shù)就怎么用)
select ename,sal,sal_tax(sal) from emp;
----觸發(fā)器
--創(chuàng)建一個(gè)日志表
create table emp2_log
(
uname varchar2(20),
action varchar2(10),
atime date
);
--創(chuàng)建一個(gè)觸發(fā)器
create or replace trigger trig
after insert or delete or update on emp2 for each row
begin
if inserting then
insert into emp2_log values (user,'insert',sysdate);
elsif updating then
insert into emp2_log values (user,'update',sysdate);
elsif deleting then
insert into emp2_log values (user,'delete',sysdate);
end if;
end;
--調(diào)用這個(gè)觸發(fā)器
update emp2 set sal = sal*2 where deptno = 30;
---更改有依賴(lài)關(guān)系的表的字段值的建立的一個(gè)觸發(fā)器
create or replace trigger trip_change
after update on dept2
for each row
begin
update emp2 set deptno = :NEW.deptno where deptno = :OLD.deptno;
end;
---觸發(fā)這個(gè)觸發(fā)器
update dept2 set deptno = 99 where deptno = 10;
---樹(shù)狀結(jié)構(gòu)的存儲(chǔ)與展示
drop table article;
create table article
(
id number primary key,
cont varchar2(4000),
pid number,
isleaf number(1),--0 代表非葉子節(jié)點(diǎn)，1 代表葉子節(jié)點(diǎn)
alevel number(2)
);
insert into article values(1,'螞蟻大戰(zhàn)大象',0,0,0);
insert into article values(2,'螞蟻大戰(zhàn)大象',1,0,1);
insert into article values(3,'螞蟻大戰(zhàn)大象',2,1,2);
insert into article values(4,'螞蟻大戰(zhàn)大象',2,0,2);
insert into article values(5,'螞蟻大戰(zhàn)大象',4,1,3);
insert into article values(6,'螞蟻大戰(zhàn)大象',1,0,1);
insert into article values(7,'螞蟻大戰(zhàn)大象',6,1,2);
insert into article values(8,'螞蟻大戰(zhàn)大象',6,1,2);
insert into article values(9,'螞蟻大戰(zhàn)大象',2,0,2);
insert into article values(10,'螞蟻大戰(zhàn)大象',9,1,3);
commit;
---用存儲(chǔ)過(guò)程展示樹(shù)狀結(jié)構(gòu)(用遞歸的方式實(shí)現(xiàn))
create or replace procedure p_tree(v_pid article.pid%type, v_level binary_integer) is
cursor c is select * from article where pid = v_pid;
v_preStr varchar2(1024) :='';
begin
for i in 1..v_level loop
v_preStr := v_preStr || '****';
end loop;
for v_article in c loop
dbms_output.put_line(v_preStr || v_article.cont);
if(v_article.isleaf = 0) then
p_tree(v_article.id, v_level + 1);
end if;
end loop;
end;
--執(zhí)行這個(gè)存儲(chǔ)過(guò)程
exec p_tree(0,0);
--SQL> exec p_tree(0,0);
--螞蟻大戰(zhàn)大象
--****螞蟻大戰(zhàn)大象
--********螞蟻大戰(zhàn)大象
--********螞蟻大戰(zhàn)大象
--************螞蟻大戰(zhàn)大象
--********螞蟻大戰(zhàn)大象
--************螞蟻大戰(zhàn)大象
--****螞蟻大戰(zhàn)大象
--********螞蟻大戰(zhàn)大象
--********螞蟻大戰(zhàn)大象
--PL/SQL 過(guò)程已成功完成。
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