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oracle練習(xí)題和答案 筆記
使用scott/tiger用戶下的emp表完成下列練習(xí)，表的結(jié)構(gòu)說明如下
emp員工表(empno員工號/ename員工姓名/job工作/mgr上級編號/hiredate受雇日期/sal薪金/comm傭金/deptno部門編號)
------1.選擇部門30中的所有員工.
select * from emp where deptno=30;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30
7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30
7698 BLAKE MANAGER 7839 01-5月 -81 2850 30
7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30
7900 JAMES CLERK 7698 03-12月-81 950 30
------2.列出所有辦事員(CLERK)的姓名，編號和部門編號.
Select empno,ename,deptno from emp where job='CLERK';
EMPNO ENAME DEPTNO
---------- ---------- ----------
7369 SMITH 20
7876 ADAMS 20
7900 JAMES 30
7934 MILLER 10
------3.找出傭金高于薪金的員工.
select * from emp where comm > sal;
比較忽略comm為空的值
select * from emp where nvl(comm,0)>sal;
nvl(col1,p) 要求col1 和 p的類型是一致的
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30
------4.找出傭金高于薪金的60%的員工.
select * from emp where nvl(comm,0)>(sal*0.6);
select * from emp where comm > sal * 60 / 100;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30
------5.找出部門10中所有經(jīng)理(MANAGER)和部門20中所有辦事員(CLERK)的詳細資料.
select * from emp where (deptno=10 and job='MANAGER') or (deptno=20 and job='CLERK');
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20
7782 CLARK MANAGER 7839 09-6月 -81 2450 10
7876 ADAMS CLERK 7788 23-5月 -87 1100 20
------6.找出部門10中所有經(jīng)理(MANAGER),部門20中所有辦事員(CLERK),
既不是經(jīng)理又不是辦事員但其薪金大于或等于2000的所有員工的詳細資料.
select * from emp
where (deptno=10 and job='MANAGER')
or (deptno=20 and job='CLERK')
or (job not in ('MANAGER','CLERK') and sal>=2000);
( job <> 'MANAGER' and job <> 'CLERK' and sal >= 2000)
!=
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20
7782 CLARK MANAGER 7839 09-6月 -81 2450 10
7788 SCOTT ANALYST 7566 19-4月 -87 3000 20
7839 KING PRESIDENT 17-11月-81 5000 10
7876 ADAMS CLERK 7788 23-5月 -87 1100 20
7902 FORD ANALYST 7566 03-12月-81 3000 20
------7.找出收取傭金的員工的不同工作.
select distinct job from emp where nvl(comm,0)>0;
distinct 消除重復(fù)值
JOB
---------
SALESMAN
------8.找出不收取傭金或收取的傭金低于100的員工.
select * from emp where nvl(comm,0)<100;
select * from emp where comm is null or comm < 100;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20
7566 JONES MANAGER 7839 02-4月 -81 2975 20
7698 BLAKE MANAGER 7839 01-5月 -81 2850 30
7782 CLARK MANAGER 7839 09-6月 -81 2450 10
7788 SCOTT ANALYST 7566 19-4月 -87 3000 20
7839 KING PRESIDENT 17-11月-81 5000 10
7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30
7876 ADAMS CLERK 7788 23-5月 -87 1100 20
7900 JAMES CLERK 7698 03-12月-81 950 30
7902 FORD ANALYST 7566 03-12月-81 3000 20
7934 MILLER CLERK 7782 23-1月 -82 1300 10
這個不對 ：select * from emp where comm < 100;
------9.找出各月倒數(shù)第3天受雇的所有員工.
last_day(日期類型) 所在月的最后一天
啞元表 dual : 當不需要表的地方可以考慮使用它
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual;
select 'Hello World' as hw from dual;
select 1+1 from dual;
select * from emp where hiredate = last_day(hiredate) - 2;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30
------10.找出早于12年前受雇的員工.
add_months(sysdate,-12*12)
返回日期類型
select * from emp where months_between(sysdate,hiredate) > 144;
select * from emp where hiredate < add_months(sysdate,-12*12);
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20
7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30
7566 JONES MANAGER 7839 02-4月 -81 2975 20
7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30
7698 BLAKE MANAGER 7839 01-5月 -81 2850 30
7782 CLARK MANAGER 7839 09-6月 -81 2450 10
7839 KING PRESIDENT 17-11月-81 5000 10
7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30
7900 JAMES CLERK 7698 03-12月-81 950 30
7902 FORD ANALYST 7566 03-12月-81 3000 20
7934 MILLER CLERK 7782 23-1月 -82 1300 10
------11.以首字母大寫的方式顯示所有員工的姓名.
select initcap(ename) as 姓名 from emp ;
姓名
----------
Smith
Allen
Ward
Jones
Martin
Blake
Clark
Scott
King
Turner
Adams
James
Ford
Miller
------12.顯示正好為5個字符的員工的姓名.
select ename from emp where length(ename)=5;
select ename from emp where ename like '_____';
like中 _ 表示一個字符
% 任意個字符
select ename from emp where ename like '張%';
select ename from emp where ename='張%';
select ename from emp where ename like '%張%';
select ename from emp where ename like 'S%';
select ename from emp where ename like '%S%';
ENAME
----------
SMITH
ALLEN
JONES
BLAKE
CLARK
SCOTT
ADAMS
JAMES
------13.顯示不帶有"R"的員工的姓名.
select ename from emp where instr(ename,'R') = 0;
select ename from emp where ename not like '%R%';
ENAME
----------
SMITH
ALLEN
JONES
BLAKE
SCOTT
KING
ADAMS
JAMES
------14.顯示所有員工姓名的前三個字符.
substr(字符,位置開始,位置結(jié)束)
select substr(ename,1,3) as ename from emp;
從第1位置開始 取3個字符
select ename,substr(ename,4) as ename1 from emp;
ENAME
------
SMI
ALL
WAR
JON
MAR
BLA
CLA
SCO
KIN
TUR
ADA
JAM
FOR
MIL
------15.顯示所有員工的姓名,用a替換所有"A"
select replace(ename,'A','a') as 替換后 from emp;
select translate(ename,'A','a') as 替換后 from emp;
替換后
---------
SMITH
aLLEN
WaRD
JONES
MaRTIN
BLaKE
CLaRK
SCOTT
KING
TURNER
aDaMS
JaMES
FORD
MILLER
------16.顯示滿10年服務(wù)年限的員工的姓名和受雇日期.
months_between(sysdate,hiredate)兩個日期之間的月數(shù)
sysdate - hiredate 天數(shù)
select ename,hiredate from emp where months_between(sysdate,hiredate)>120;
select ename,hiredate from emp where sysdate>add_months(hiredate,120);
ENAME HIREDATE
---------- ----------
SMITH 17-12月-80
ALLEN 20-2月 -81
WARD 22-2月 -81
JONES 02-4月 -81
MARTIN 28-9月 -81
BLAKE 01-5月 -81
CLARK 09-6月 -81
SCOTT 19-4月 -87
KING 17-11月-81
TURNER 08-9月 -81
ADAMS 23-5月 -87
JAMES 03-12月-81
FORD 03-12月-81
MILLER 23-1月 -82
不對：select ename,hiredate from emp where months_between(hiredate,sysdate)>120;
(<-120)
------17.顯示員工的詳細資料,按姓名排序.
select * from emp order by ename;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7876 ADAMS CLERK 7788 23-5月 -87 1100 20
7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30
7698 BLAKE MANAGER 7839 01-5月 -81 2850 30
7782 CLARK MANAGER 7839 09-6月 -81 2450 10
7902 FORD ANALYST 7566 03-12月-81 3000 20
7900 JAMES CLERK 7698 03-12月-81 950 30
7566 JONES MANAGER 7839 02-4月 -81 2975 20
7839 KING PRESIDENT 17-11月-81 5000 10
7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30
7934 MILLER CLERK 7782 23-1月 -82 1300 10
7788 SCOTT ANALYST 7566 19-4月 -87 3000 20
7369 SMITH CLERK 7902 17-12月-80 800 20
7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30
------18.顯示員工的姓名和受雇日期,根據(jù)其服務(wù)年限,將最老的員工排在最前面.
select ename,hiredate from emp order by hiredate;
ENAME HIREDATE
---------- ----------
SMITH 17-12月-80
ALLEN 20-2月 -81
WARD 22-2月 -81
JONES 02-4月 -81
BLAKE 01-5月 -81
CLARK 09-6月 -81
TURNER 08-9月 -81
MARTIN 28-9月 -81
KING 17-11月-81
JAMES 03-12月-81
FORD 03-12月-81
MILLER 23-1月 -82
SCOTT 19-4月 -87
ADAMS 23-5月 -87
------19.顯示所有員工的姓名、工作和薪金,按工作的降序排序,若工作相同則按薪金排序.
select ename,job,sal from emp order by job desc,sal;
ENAME JOB SAL
---------- --------- ----------
WARD SALESMAN 1250
MARTIN SALESMAN 1250
TURNER SALESMAN 1500
ALLEN SALESMAN 1600
KING PRESIDENT 5000
CLARK MANAGER 2450
BLAKE MANAGER 2850
JONES MANAGER 2975
SMITH CLERK 800
JAMES CLERK 950
ADAMS CLERK 1100
MILLER CLERK 1300
SCOTT ANALYST 3000
FORD ANALYST 3000
------20.顯示所有員工的姓名、加入公司的年份和月份,按受雇日期所在月排序,
若月份相同則將最早年份的員工排在最前面.
select to_char(sysdate,'day') from dual;
select to_char(sysdate,'ddd') from dual;
select to_char(sysdate,'dd') from dual;
select to_char(sysdate,'mm') from dual;
select to_char(sysdate,'month') from dual;
select to_char(sysdate,'yyyy') from dual;
select to_char(sysdate,'hh24:mi:ss') from dual;
select ename,to_char(Hiredate,'yyyy"年"mm"月"') as 年月,hiredate from emp
order by to_char(Hiredate,'mm'),to_char(Hiredate,'yyyy');
ENAME 年月 HIREDATE
---------- ---------- ----------
MILLER 1982年01月 23-1月 -82
ALLEN 1981年02月 20-2月 -81
WARD 1981年02月 22-2月 -81
JONES 1981年04月 02-4月 -81
SCOTT 1987年04月 19-4月 -87
BLAKE 1981年05月 01-5月 -81
ADAMS 1987年05月 23-5月 -87
CLARK 1981年06月 09-6月 -81
MARTIN 1981年09月 28-9月 -81
TURNER 1981年09月 08-9月 -81
KING 1981年11月 17-11月-81
SMITH 1980年12月 17-12月-80
JAMES 1981年12月 03-12月-81
FORD 1981年12月 03-12月-81
select ename,to_char(Hiredate,'yyyy/mm') as 年月,hiredate from emp
order by to_char(Hiredate,'mm'),to_char(Hiredate,'yyyy');
------21.顯示在一個月為30天的情況所有員工的日薪金,忽略余數(shù).
忽略余數(shù)/截斷
trunc(17.25) 17
trunc(19.98) 19
trunc(19.98,1) 19.9
四舍五入
round(20.5) 21
round(20.88,1) 21.9
select ename,trunc(sal/30) daysal from emp;
ENAME DAYSAL
---------- ----------
SMITH 26
ALLEN 53
WARD 41
JONES 99
MARTIN 41
BLAKE 95
CLARK 81
SCOTT 100
KING 166
TURNER 50
ADAMS 36
JAMES 31
FORD 100
MILLER 43
------22.找出在(任何年份的)2月受聘的所有員工。
select * from emp where to_char(hiredate,'mm')='02';
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30
------23.對于每個員工,顯示其加入公司的天數(shù).
floor 向下取整,不超過這個數(shù)最大整數(shù)
floor(21.5) 21
floor(-21.5) -22
ceil 向上取整,不小于這個數(shù)的最小整數(shù)
ceil(12.5) 13
ceil(-12.5) -12
select ename,floor(sysdate-hiredate) totdays from emp;
ENAME TOTDAYS
---------- ----------
SMITH 8721
ALLEN 8656
WARD 8654
JONES 8615
MARTIN 8436
BLAKE 8586
CLARK 8547
SCOTT 6407
KING 8386
TURNER 8456
ADAMS 6373
JAMES 8370
FORD 8370
MILLER 8319
------24.顯示姓名字段的任何位置包含"A"的所有員工的姓名.
select * from emp where instr(ename,'A')>0;
select * from emp where ename like '%A%';
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30
7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30
7698 BLAKE MANAGER 7839 01-5月 -81 2850 30
7782 CLARK MANAGER 7839 09-6月 -81 2450 10
7876 ADAMS CLERK 7788 23-5月 -87 1100 20
7900 JAMES CLERK 7698 03-12月-81 950 30
------25.以年月日的方式顯示所有員工的服務(wù)年限. (大概)
mod 取余數(shù)
mod(12,3) 0
mod(5,2) 1
mod(4,2) 0
to_date
日期轉(zhuǎn)換
select to_date('1999-09-05','yyyy-mm-dd') from dual
select empno,ename,('在職'||trunc((months_between(sysdate,hiredate))/12)||'年'
||trunc(mod((months_between(sysdate,hiredate)),12))||'個月'
||round(sysdate-(add_months(hiredate,months_between(sysdate,hiredate))))||'天') tot from emp;
select ename,
to_char(to_date('0001-01-01','yyyy-mm-dd')+(sysdate-hiredate)-366-31,'yy:mm:dd') as tot, trunc(sysdate-hiredate) as 天數(shù) from emp;
to_number
數(shù)字轉(zhuǎn)換
select to_number('1999') from dual;
select to_number('abc') from dual;
asc碼
select ascii('A') from dual;
select chr(65) from dual;
連接函數(shù)
||
select to_char(sysdate,'yyyy"年"mm"月"') from dual;
select to_char(sysdate,'yyyy')||'年'||to_char(sysdate,'mm')||'月' from dual;
decode函數(shù)
if ... else if .... else
sal=800 顯示低工資
sal=5000 顯示高工資
其他sal 顯示正常工資
等值比較
select ename,sal,decode(sal,800,'低工資',5000,'高工資','正常工資') as 工資狀態(tài)
from emp;
decode(sal,800,'低工資',5000,'高工資','正常工資') 相當于
<等值比較>
if sal =800 then
顯示 '低工資'
else if sal=5000 then
顯示 '高工資'
else
顯示 '正常工資'
end if
x > 1600 變成 x-1600 > 0
符號函數(shù)sign 判斷數(shù)的正/負/零
select sign(-12) from dual; -1代表負數(shù)
select sign(12) from dual; 1 代表正數(shù)
select sign(0) from dual; 0 代表0
sal<1600 顯示低工資
1600=<sal<=3000 顯示正常工資
>3000 顯示高工資
select ename,sal,decode(sign(sal-1600),-1,'低工資',
decode(sign(sal-3000),-1,'正常工資',0,'正常工資',1,'高工資')) as 工資狀態(tài)
from emp;
相當于
if sign(sal-1600) = -1 then
顯示 '低工資'
else
if sign(sal-3000) = -1 then
顯示 '正常工資'
else if sign(sal-3000) = 0 then
顯示 '正常工資'
else
顯示 '高工資'
end if
end if
