Oracle学习02【持续更新】

Oracle继续学习中。。。。。。

查询职位是"MANAGER"或职位不是"ANALYST"的员工（方式一）

select * from emp where job='MANAGER' or not(job='ANALYST');

sql> select * from emp where job='MANAGER' or not(job='ANALYST');

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
 7876 ADAMS      CLERK       7788 23-5月 -87    1100           20
 7900 JAMES      CLERK       7698 03-12月-81     950           30
 7934 MILLER     CLERK       7782 23-1月 -82    1300           10

已选择12行。

查询职位是"MANAGER"或职位不是"ANALYST"的员工（方式二）:select * from emp where job='MANAGER' or job!='ANALYST';

sql> select * from emp where job='MANAGER' or job !='ANALYST';

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
 7876 ADAMS      CLERK       7788 23-5月 -87    1100           20
 7900 JAMES      CLERK       7698 03-12月-81     950           30
 7934 MILLER     CLERK       7782 23-1月 -82    1300           10

已选择12行。

查询员工信息，按薪水升序排序:select * from emp order by sal desc;

sql> select * from emp order by sal desc;

EMPNO ENAME      JOB          MGR HIREDATE       SAL  COMM DEPTNO
----- ---------- ---------- ----- ------------ ----- ----- ------
 7839 KING       PRESIDENT        17-11月-81    5000           10
 7902 FORD       ANALYST     7566 03-12月-81    3000           20
 7788 SCOTT      ANALYST     7566 19-4月 -87    3000           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
 7499 ALLEN      SALESMAN    7698 20-2月 -81    1600   300     30
 7844 TURNER     SALESMAN    7698 08-9月 -81    1500     0     30
 7934 MILLER     CLERK       7782 23-1月 -82    1300           10
 7521 WARD       SALESMAN    7698 22-2月 -81    1250   500     30
 7654 MARTIN     SALESMAN    7698 28-9月 -81    1250  1400     30
 7876 ADAMS      CLERK       7788 23-5月 -87    1100           20
 7900 JAMES      CLERK       7698 03-12月-81     950           30
 7369 SMITH      CLERK       7902 17-12月-80     800           20

已选择14行。

查询员工信息，按入职日期降序排序：select * from emp order by hiredate desc;

sql> select * from emp order by hiredate desc;

EMPNO ENAME      JOB          MGR HIREDATE       SAL  COMM DEPTNO
----- ---------- ---------- ----- ------------ ----- ----- ------
 7876 ADAMS      CLERK       7788 23-5月 -87    1100           20
 7788 SCOTT      ANALYST     7566 19-4月 -87    3000           20
 7934 MILLER     CLERK       7782 23-1月 -82    1300           10
 7902 FORD       ANALYST     7566 03-12月-81    3000           20
 7900 JAMES      CLERK       7698 03-12月-81     950           30
 7839 KING       PRESIDENT        17-11月-81    5000           10
 7654 MARTIN     SALESMAN    7698 28-9月 -81    1250  1400     30
 7844 TURNER     SALESMAN    7698 08-9月 -81    1500     0     30
 7782 CLARK      MANAGER     7839 09-6月 -81    2450           10
 7698 BLAKE      MANAGER     7839 01-5月 -81    2850           30
 7566 JONES      MANAGER     7839 02-4月 -81    2975           20
 7521 WARD       SALESMAN    7698 22-2月 -81    1250   500     30
 7499 ALLEN      SALESMAN    7698 20-2月 -81    1600   300     30
 7369 SMITH      CLERK       7902 17-12月-80     800           20

已选择14行

order by后面可以跟列名、别名、表达式、列号
select * from emp order by sal desc;

select empno "编号",ename "姓名",sal "工资" from emp order by "工资" desc;

sql> select empno "编号",sal "工 资" from emp order by "工 资" desc
;

      编号 姓名                      工 资
---------- -------------------- ----------
      7839 KING                       5000
      7902 FORD                       3000
      7788 SCOTT                      3000
      7566 JONES                      2975
      7698 BLAKE                      2850
      7782 CLARK                      2450
      7499 ALLEN                      1600
      7844 TURNER                     1500
      7934 MILLER                     1300
      7521 WARD                       1250
      7654 MARTIN                     1250
      7876 ADAMS                      1100
      7900 JAMES                       950
      7369 SMITH                       800

已选择14行。

select empno "编号",sal "工资",sal*12 "年薪" from emp order by sal*12 desc;

sql> select empno "编号",sal*12 "年薪" from emp order by
 sal*12 desc;

      编号 姓名                       工资       年薪
---------- -------------------- ---------- ----------
      7839 KING                       5000      60000
      7902 FORD                       3000      36000
      7788 SCOTT                      3000      36000
      7566 JONES                      2975      35700
      7698 BLAKE                      2850      34200
      7782 CLARK                      2450      29400
      7499 ALLEN                      1600      19200
      7844 TURNER                     1500      18000
      7934 MILLER                     1300      15600
      7521 WARD                       1250      15000
      7654 MARTIN                     1250      15000
      7876 ADAMS                      1100      13200
      7900 JAMES                       950      11400
      7369 SMITH                       800       9600

已选择14行。

select empno "编号",sal*12 "年薪" from emp order by 4 desc;

sql> select empno "编号",sal*12 "年薪" from emp order by
 4 desc;

      编号 姓名                       工资       年薪
---------- -------------------- ---------- ----------
      7839 KING                       5000      60000
      7902 FORD                       3000      36000
      7788 SCOTT                      3000      36000
      7566 JONES                      2975      35700
      7698 BLAKE                      2850      34200
      7782 CLARK                      2450      29400
      7499 ALLEN                      1600      19200
      7844 TURNER                     1500      18000
      7934 MILLER                     1300      15600
      7521 WARD                       1250      15000
      7654 MARTIN                     1250      15000
      7876 ADAMS                      1100      13200
      7900 JAMES                       950      11400
      7369 SMITH                       800       9600

已选择14行。

查询员工信息，按佣金升序或降序排列，null值放后面（nulls last）

select * from emp order by comm asc;

sql> select * from emp order by comm asc;

EMPNO ENAME      JOB          MGR HIREDATE       SAL  COMM DEPTNO
----- ---------- ---------- ----- ------------ ----- ----- ------
 7844 TURNER     SALESMAN    7698 08-9月 -81    1500     0     30
 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
 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
 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
 7698 BLAKE      MANAGER     7839 01-5月 -81    2850           30
 7566 JONES      MANAGER     7839 02-4月 -81    2975           20
 7369 SMITH      CLERK       7902 17-12月-80     800           20
 7782 CLARK      MANAGER     7839 09-6月 -81    2450           10

已选择14行。

select * from emp order by comm desc nulls last;

sql> select * from emp order by comm desc nulls last;

EMPNO ENAME      JOB          MGR HIREDATE       SAL  COMM DEPTNO
----- ---------- ---------- ----- ------------ ----- ----- ------
 7654 MARTIN     SALESMAN    7698 28-9月 -81    1250  1400     30
 7521 WARD       SALESMAN    7698 22-2月 -81    1250   500     30
 7499 ALLEN      SALESMAN    7698 20-2月 -81    1600   300     30
 7844 TURNER     SALESMAN    7698 08-9月 -81    1500     0     30
 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
 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
 7698 BLAKE      MANAGER     7839 01-5月 -81    2850           30
 7566 JONES      MANAGER     7839 02-4月 -81    2975           20
 7369 SMITH      CLERK       7902 17-12月-80     800           20
 7782 CLARK      MANAGER     7839 09-6月 -81    2450           10

已选择14行。

查询员工信息，按工资降序排列,相同工资的员工再按入职时间降序排列

select * from emp order by sal desc,hiredate desc;

sql> select * from emp order by sal desc,hiredate desc;

EMPNO ENAME      JOB          MGR HIREDATE       SAL  COMM DEPTNO
----- ---------- ---------- ----- ------------ ----- ----- ------
 7839 KING       PRESIDENT        17-11月-81    5000           10
 7788 SCOTT      ANALYST     7566 19-4月 -87    3000           20
 7902 FORD       ANALYST     7566 03-12月-81    3000           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
 7499 ALLEN      SALESMAN    7698 20-2月 -81    1600   300     30
 7844 TURNER     SALESMAN    7698 08-9月 -81    1500     0     30
 7934 MILLER     CLERK       7782 23-1月 -82    1300           10
 7654 MARTIN     SALESMAN    7698 28-9月 -81    1250  1400     30
 7521 WARD       SALESMAN    7698 22-2月 -81    1250   500     30
 7876 ADAMS      CLERK       7788 23-5月 -87    1100           20
 7900 JAMES      CLERK       7698 03-12月-81     950           30
 7369 SMITH      CLERK       7902 17-12月-80     800           20

已选择14行。

测试LOWER/UPPER/INITCAP函数
select lower('Hello World') "转小写",upper('Hello World') "转大写",initcap('hello world') "首字母大写"from dual;

sql> select lower('Hello World') "转小写",initcap(
'hello world') "首字母大写" from dual;

转小写                 转大写                 首字母大写
---------------------- ---------------------- ----------------------
hello world            HELLO WORLD            Hello World

测试CONCAT/SUBSTR函数，从1开始：
select concat('hello',' world') "字符串拼接",substr('hello world',7,11) "字符串截取"from dual;

sql> select concat('hello',11) "字
符串截取" from dual;

字符串拼接             字符串截取
---------------------- ----------
hello world            world

测试LENGTH/LENGTHB函数：

select length('中CHINA') "字符",lengthb('中CHINA') "字节"from dual;

sql> select length('中CHINA') "字符",lengthb('中CHINA') "字节" from dual;

      字符       字节
---------- ----------
         6          8

length：不管中英文，都是1位

lengthb：英文，是1位；中文是3位【unicode即utf-8】
测试INSTR/LPAD/RPAD函数

sql> select instr('hello world','o'),lpad('haha',10,'#'),rpad('hehe','@') fro
m dual;

INSTR('HELLOWORLD','O') LPAD('HAHA','#')  RPAD('HEHE','@')
----------------------- -------------------- --------------------
                      5 ######haha           hehe@@@@@@

测试TRIM/REPLACE函数

select trim('x' from 'xxxHELLOxxxWORLDxxx'),replace('abcd','c','$')from dual;

sql> select trim('x' from 'xxxHELLOxxxWORLDxxx'),'$') from du
al;

TRIM('X'FROM'XXXHELLOXXXWO REPLACE(
-------------------------- --------
HELLOxxxWORLD              ab$d

select trim(' ' from ' HELLO WORLD ')from dual;

sql> select trim(' ' from '   HELLO   WORLD   ') from dual;

TRIM(''FROM'HELLOWORLD')
--------------------------
HELLO   WORLD

测试ROUND/TRUNC/MOD函数
select round(3.1415926,3),trunc(3.1415926,mod(1000,300)from dual;

sql> select round(3.1415926,300) from dual;

ROUND(3.1415926,3) TRUNC(3.1415926,3) MOD(1000,300)
------------------ ------------------ -------------
             3.142              3.141           100

select round(sysdate,'month') from dual;

sql> select round(sysdate,'month') from dual;

ROUND(SYSDATE,--------------
01-7月 -16

select trunc(sysdate,'month')from dual;

sql> select trunc(sysdate,'month') from dual;

TRUNC(SYSDATE,--------------
01-6月 -16

显示昨天，今天，明天的日期
select sysdate-1 "昨天",sysdate "今天",sysdate+1 明天from dual;

sql> select sysdate-1 "昨天",sysdate+1 明天 from dual;

昨天           今天           明天
-------------- -------------- --------------
19-6月 -16     20-6月 -16     21-6月 -16

以年和月形式显示员工近似工龄
select ename "姓名",sysdate-hiredate "日工龄",(sysdate-hiredate)/30 "月工龄",(sysdate-hiredate)/365 "年工龄"from emp;

sql> select ename "姓名",(sysdate-hiredate)/30 "月工龄
",(sysdate-hiredate)/365 "年工龄" from emp;

姓名                     日工龄     月工龄     年工龄
-------------------- ---------- ---------- ----------
SMITH                 12969.987 432.332899 35.5342109
ALLEN                 12904.987 430.166232 35.3561287
WARD                  12902.987 430.099566 35.3506492
JONES                 12863.987 428.799566 35.2437999
MARTIN                12684.987 422.832899  34.753389
BLAKE                 12834.987 427.832899 35.1643479
CLARK                 12795.987 426.532899 35.0574985
SCOTT                 10655.987 355.199566 29.1944848
KING                  12634.987 421.166232 34.6164027
TURNER                12704.987 423.499566 34.8081835
ADAMS                 10621.987 354.066232 29.1013342
JAMES                 12618.987 420.632899  34.572567
FORD                  12618.987 420.632899  34.572567
MILLER                12567.987 418.932899  34.432841

已选择14行。

使用MONTHS_BETWEEN函数，以精确月形式显示员工工龄
select ename "姓名",(sysdate-hiredate)/30 "近似月工龄",months_between(sysdate,hiredate) "精确月工龄"from emp;

sql> select ename "姓名",months_between(sysda
te,hiredate) "精确月工龄" from emp;

姓名                 近似月工龄 精确月工龄
-------------------- ---------- ----------
SMITH                432.332915 426.128627
ALLEN                430.166248        424
WARD                 430.099581 423.967337
JONES                428.799581 422.612498
MARTIN               422.832915 416.773788
BLAKE                427.832915 421.644756
CLARK                426.532915 420.386692
SCOTT                355.199581 350.064111
KING                 421.166248 415.128627
TURNER               423.499581  417.41895
ADAMS                354.066248 348.935079
JAMES                420.632915  414.58024
FORD                 420.632915  414.58024
MILLER               418.932915 412.935079

已选择14行。

测试ADD_MONTHS函数

select add_months(sysdate,3)from dual;

sql> select add_months(sysdate,3) from dual;

ADD_MONTHS(SYS
--------------
20-9月 -16

测试NEXT_DAY函数【中文平台】

select next_day(sysdate,'星期三')from dual;

sql> select next_day(sysdate,'星期三') from dual;

NEXT_DAY(SYSDA
--------------
22-6月 -16

从今天开始算，下一个星期三是多少号？

select next_day(next_day(sysdate,'星期三'),'星期三')from dual;

sql> select next_day(next_day(sysdate,'星期三') from dual;

NEXT_DAY(NEXT_
--------------
29-6月 -16

日期隐式转换，读字符串，判断是否符合日期格式要求，再隐式转换，效率低
select ename,hiredate from emp where hiredate='17-12月-80';
隐式转换
'123'字符串-->123数值
'1-1月-13'--->1-1月-13
123---------->'123'
1-1月-13----->'1-1月-13'
日期显式转换，效率高，项目中提倡使用
select ename,to_char(hiredate,'yyyy-mm-dd')from emp where hiredate=to_date('1980-12-17','yyyy-mm-dd');

sql> select ename,'yyyy-mm-dd') from emp where hiredate=to_date
('1980-12-17','yyyy-mm-dd');

ENAME      TO_CHAR(HIREDATE,'YY
---------- --------------------
SMITH      1980-12-17

使用to_char()函数将日期转成字符串，显示如下格式：2012-12-1 今天是星期六 20:12:47
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss')from dual;

sql> select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual;

TO_CHAR(SYSDATE,'YYYY-MM-DDHH24:MI:SS'
--------------------------------------
2016-06-20 23:48:23

select to_char(sysdate,'YYYY-MM-DD-DAY HH:MI:SS AM')from dual;

sql> select to_char(sysdate,'YYYY-MM-DD-DAY HH:MI:SS AM')from dual;

TO_CHAR(SYSDATE,'YYYY-MM-DD-DAYHH:MI:SSAM')
--------------------------------------------------------------------
2016-06-20-星期一 11:50:02 下午

select to_char(sysdate,'yyyy-mm-dd "今天是" day hh24:mi:ss') "时间"from dual;
常量一定要用""双引号定界

sql> select to_char(sysdate,'yyyy-mm-dd "今天是" day hh24:mi:ss') "时间"from dua
l;

时间
--------------------------------------------------------------------------------

2016-06-20 今天是 星期一 23:50:35

显示员工工资，加上$或￥符号和千位符
select ename,to_char(sal,'$9,999') from emp;
select ename,'L9,999') from emp;

sql> select ename,999') from emp;

ENAME      TO_CHAR(SAL,'$
---------- --------------
SMITH         $800
ALLEN       $1,600
WARD        $1,250
JONES       $2,975
MARTIN      $1,250
BLAKE       $2,850
CLARK       $2,450
SCOTT       $3,000
KING        $5,000
TURNER      $1,500
ADAMS       $1,100
JAMES         $950
FORD        $3,000
MILLER      $1,300

已选择14行。

sql> select ename,999')
---------- --------------------------------
SMITH                ￥800
ALLEN              ￥1,600
WARD               ￥1,250
JONES              ￥2,975
MARTIN             ￥1,250
BLAKE              ￥2,850
CLARK              ￥2,450
SCOTT              ￥3,000
KING               ￥5,000
TURNER             ￥1,500
ADAMS              ￥1,100
JAMES                ￥950
FORD               ￥3,000
MILLER             ￥1,300

已选择14行。

使用to_number()函数将字符串转成数字
select to_number('123')+100 "结果"from dual;

sql> select to_number('123')+100 "结果" from dual;

      结果
----------
       223

使用nul函数，统计员工年收入
select ename,12*sal+nvl(comm,0)from emp;

sql> select ename,0) from emp;

ENAME      12*SAL+NVL(COMM,0)
---------- ------------------
SMITH                    9600
ALLEN                   19500
WARD                    15500
JONES                   35700
MARTIN                  16400
BLAKE                   34200
CLARK                   29400
SCOTT                   36000
KING                    60000
TURNER                  18000
ADAMS                   13200
JAMES                   11400
FORD                    36000
MILLER                  15600

已选择14行。

使用nul2函数，统计员工年收入
使用nullif函数，比较10和10.0是否相同
select nullif(10,10.0)from dual;

使用case表达式，职位是总载的，工资+1000；职位是经理的，工资+800；职位是其它的，工资+400
select ename,job,sal,
case job
when 'PRESIDENT' then sal+1000
when 'MANAGER' then sal+800
else sal+400
end "涨后薪水"

from emp;

sql> select ename,2         case job
  3              when 'PRESIDENT' then sal+1000
  4              when 'MANAGER'   then sal+800
  5              else  sal+400
  6         end "涨后薪水"
  7  from emp;

ENAME      JOB          SAL   涨后薪水
---------- ---------- ----- ----------
SMITH      CLERK        800       1200
ALLEN      SALESMAN    1600       2000
WARD       SALESMAN    1250       1650
JONES      MANAGER     2975       3775
MARTIN     SALESMAN    1250       1650
BLAKE      MANAGER     2850       3650
CLARK      MANAGER     2450       3250
SCOTT      ANALYST     3000       3400
KING       PRESIDENT   5000       6000
TURNER     SALESMAN    1500       1900
ADAMS      CLERK       1100       1500
JAMES      CLERK        950       1350
FORD       ANALYST     3000       3400
MILLER     CLERK       1300       1700

已选择14行。

各数据库厂都支持ANSIsql标准
使用decode函数，职位是总载的，工资+1000；职位是经理的，工资+800；职位是其它的，工资+400
select ename,sal 涨前薪水,
decode(job,'PRESIDENT',sal+1000,'MANAGER',sal+800,sal+400) "涨后薪水" from emp;
decode函数专用

sql> select ename,2         decode(job,sal+400) "涨后薪水
" from emp;

ENAME      JOB          涨前薪水   涨后薪水
---------- ---------- ---------- ----------
SMITH      CLERK             800       1200
ALLEN      SALESMAN         1600       2000
WARD       SALESMAN         1250       1650
JONES      MANAGER          2975       3775
MARTIN     SALESMAN         1250       1650
BLAKE      MANAGER          2850       3650
CLARK      MANAGER          2450       3250
SCOTT      ANALYST          3000       3400
KING       PRESIDENT        5000       6000
TURNER     SALESMAN         1500       1900
ADAMS      CLERK            1100       1500
JAMES      CLERK             950       1350
FORD       ANALYST          3000       3400
MILLER     CLERK            1300       1700

已选择14行。

员工总工资，平均工资
select sum(sal) "总工资",round(avg(sal),2) "平均工资"from emp;

sql> select sum(sal) "总工资",2) "平均工资" from emp;

    总工资   平均工资
---------- ----------
     29025    2073.21

员工最高工资，最低工资
select max(sal) "最高工资",min(sal) "最低工资"from emp;

sql> select max(sal) "最高工资",min(sal) "最低工资" from emp;

  最高工资   最低工资
---------- ----------
      5000        800

入职最早员工，入职最晚员工
select max(hiredate) "最晚入职员工",min(hiredate) "最早入职员工"from emp;

sql> select max(hiredate) "最晚入职员工",min(hiredate) "最早入职员工" from emp;


最晚入职员工   最早入职员工
-------------- --------------
23-5月 -87     17-12月-80

求员工总人数
select count(*) 员工总人数from emp;

sql> select count(*) 员工总人数 from emp;

员工总人数
----------
        14

统计有佣金的员工人数

select count(comm) 有佣金的员工人数from emp;

sql> select count(comm) 有佣金的员工人数 from emp;

有佣金的员工人数
----------------
               4

分组函数不统计null值
统计公司有多少个部门

sql> select count(distinct deptno) from emp;

COUNT(DISTINCTDEPTNO)
---------------------
                    3

按部门求出部门平均工资
--以下sql语句是正确
select deptno,trunc(avg(sal),0)from empgroup by deptno;

sql> select deptno,0) from emp group by deptno;

DEPTNO TRUNC(AVG(SAL),0)
------ -----------------
    30              1566
    20              2175
    10              2916

select trunc(avg(sal),0)from empgroup by deptno;

sql> select trunc(avg(sal),0) from emp group by deptno;

TRUNC(AVG(SAL),0)
-----------------
             1566
             2175
             2916

--以下sql语句是错误，原因在于select子句中的非组函数没有全部出现在group by子句中
select ename,deptno,0)
from emp
group by ename;

查询部门平均工资大于2000元的部门
select deptno,0) "部门平均工资"
from emp
group by deptno
having trunc(avg(sal),0)>2000;

sql> select deptno,0) "部门平均工资"
  2  from emp
  3  group by deptno
  4  having trunc(avg(sal),0)>2000;

DEPTNO 部门平均工资
------ ------------
    20         2175
    10         2916

除10号部门外，查询部门平均工资大于2000元的部门
方式一
select deptno,0)>2000 and deptno!=10;

sql> select deptno,0)>2000 and deptno!=10;

DEPTNO 部门平均工资
------ ------------
    20         2175

方式二【先行过滤，再组过滤，性能较佳】
select deptno,0) "部门平均工资"
from emp
where deptno!=10
group by deptno
having trunc(avg(sal),0)>2000;

sql> select deptno,0) "部门平均工资"
  2  from emp
  3  where deptno!=10
  4  group by deptno
  5  having trunc(avg(sal),0)>2000;

DEPTNO 部门平均工资
------ ------------
    20         2175

显示部门平均工资的最大值
select max(avg(sal))
from emp

group by deptno;

sql> select max(avg(sal))
  2  from emp
  3  group by deptno;

MAX(AVG(SAL))
-------------
   2916.66667

原文链接：https://www.f2er.com/oracle/213937.html

Oracle学习02【持续更新】

猜你在找的Oracle相关文章