课程复习（一）

课程复习

1.ORACLE的四个用户

超级管理员：sys （change_on_install);

普通管理员：system（manager）；

普通用户：scott、hr

2.sqlplus 的主要操作命令：@、ed、conn、set、shutdown immediate、statup；

3.SQL语法的基本格式：

SELECT [DISTINCT] * |列 [别名]，[列 别名，...]
FROM 表名称 [别名]
[WHERE 条件（s）]
[ORDER BY 排序字段 ASC|DESC [排序字段 ASC|DESC]];

其中对于WHERE而言，可以使用关系运算符、逻辑运算符、BETWEEN...AND、LIKE、IN、IS(NOT)NULL;

4.单行函数：UPPER()、LOWER()、INITCAP()、REPLACE()、LENGTH()、SUBSTR()、ROUND()、TRUNC()、MOD（）、LAST_DAY（)、NEXT_DAY()、MONTHS_BETWEEN（）、ADD_MONTHS()、SYSDATE、TO_CHAR（）、TO_DATE()、NVL()、DECODE()，以上的函数知道怎么使用即可，以后使用到了相关的功能之后，能用就行；

5.日期的计算：

日期+数字=日期；

日期-数字=日期；

日期-日期=数字（天数）；

在很多语言之中，日期可以和数字互相转换；

习题：

1.选择部门60中的所有的员工。

EMPLOYEE_ID FIRST_NAME           LAST_NAME                 EMAIL                     PHONE_NUMBER         HIRE_DATE   JOB_ID         SALARY COMMISSION_PCT MANAGER_ID DEPARTMENT_ID
----------- -------------------- ------------------------- ------------------------- -------------------- ----------- ---------- ---------- -------------- ---------- -------------
        103 Alexander            Hunold                    AHUNOLD                   590.423.4567         1990-01-03  IT_PROG       9000.00                       102            60
        104 Bruce                Ernst                     BERNST                    590.423.4568         1991-05-21  IT_PROG       6000.00                       103            60
        105 David                Austin                    DAUSTIN                   590.423.4569         1997-06-25  IT_PROG       4800.00                       103            60
        106 Valli                Pataballa                 VPATABAL                  590.423.4560         1998-02-05  IT_PROG       4800.00                       103            60
        107 Diana                Lorentz                   DLORENTZ                  590.423.5567         1999-02-07  IT_PROG       4200.00                       103            60

2.列出所有办事员（SH_CLERK)的姓名，编号的部门编号；

SQL> SELECT first_name,job_id,employee_id,department_id FROM employees WHERE job_id='SH_CLERK';
FIRST_NAME           JOB_ID     EMPLOYEE_ID DEPARTMENT_ID
-------------------- ---------- ----------- -------------
Donald               SH_CLERK           198            50
Douglas              SH_CLERK           199            50
Winston              SH_CLERK           180            50
Jean                 SH_CLERK           181            50
Martha               SH_CLERK           182            50
Girard               SH_CLERK           183            50
Nandita              SH_CLERK           184            50
Alexis               SH_CLERK           185            50
Julia                SH_CLERK           186            50
Anthony              SH_CLERK           187            50
Kelly                SH_CLERK           188            50
Jennifer             SH_CLERK           189            50
Timothy              SH_CLERK           190            50
Randall              SH_CLERK           191            50
Sarah                SH_CLERK           192            50
Britney              SH_CLERK           193            50
Samuel               SH_CLERK           194            50
Vance                SH_CLERK           195            50
Alana                SH_CLERK           196            50
Kevin                SH_CLERK           197            50
20 rows selected

3.找出佣金高于年薪

SQL> SELECT * FROM employees WHERE commission_pct>salary;

4.找出部门80中所有经理（manager）和部门50中所有办事员（SH_CLERK)的详细信息；

SQL> SELECT * FROM employees WHERE (department_id=80 AND job_id='SA_MAN') OR (department_id=50 AND job_id='SH_CLERK');
EMPLOYEE_ID FIRST_NAME           LAST_NAME                 EMAIL                     PHONE_NUMBER         HIRE_DATE   JOB_ID         SALARY COMMISSION_PCT MANAGER_ID DEPARTMENT_ID
----------- -------------------- ------------------------- ------------------------- -------------------- ----------- ---------- ---------- -------------- ---------- -------------
        145 John                 Russell                   JRUSSEL                   011.44.1344.429268   1996-10-01  SA_MAN       14000.00           0.40        100            80
        146 Karen                Partners                  KPARTNER                  011.44.1344.467268   1997-01-05  SA_MAN       13500.00           0.30        100            80
        147 Alberto              Errazuriz                 AERRAZUR                  011.44.1344.429278   1997-03-10  SA_MAN       12000.00           0.30        100            80
        148 Gerald               Cambrault                 GCAMBRAU                  011.44.1344.619268   1999-10-15  SA_MAN       11000.00           0.30        100            80
        149 Eleni                Zlotkey                   EZLOTKEY                  011.44.1344.429018   2000-01-29  SA_MAN       10500.00           0.20        100            80
        198 Donald               OConnell                  DOCONNEL                  650.507.9833         1999-06-21  SH_CLERK      2600.00                       124            50
        199 Douglas              Grant                     DGRANT                    650.507.9844         2000-01-13  SH_CLERK      2600.00                       124            50
        180 Winston              Taylor                    WTAYLOR                   650.507.9876         1998-01-24  SH_CLERK      3200.00                       120            50
        181 Jean                 Fleaur                    JFLEAUR                   650.507.9877         1998-02-23  SH_CLERK      3100.00                       120            50
        182 Martha               Sullivan                  MSULLIVA                  650.507.9878         1999-06-21  SH_CLERK      2500.00                       120            50
        183 Girard               Geoni                     GGEONI                    650.507.9879         2000-02-03  SH_CLERK      2800.00                       120            50
        184 Nandita              Sarchand                  NSARCHAN                  650.509.1876         1996-01-27  SH_CLERK      4200.00                       121            50
        185 Alexis               Bull                      ABULL                     650.509.2876         1997-02-20  SH_CLERK      4100.00                       121            50
        186 Julia                Dellinger                 JDELLING                  650.509.3876         1998-06-24  SH_CLERK      3400.00                       121            50
        187 Anthony              Cabrio                    ACABRIO                   650.509.4876         1999-02-07  SH_CLERK      3000.00                       121            50
        188 Kelly                Chung                     KCHUNG                    650.505.1876         1997-06-14  SH_CLERK      3800.00                       122            50
        189 Jennifer             Dilly                     JDILLY                    650.505.2876         1997-08-13  SH_CLERK      3600.00                       122            50
        190 Timothy              Gates                     TGATES                    650.505.3876         1998-07-11  SH_CLERK      2900.00                       122            50
        191 Randall              Perkins                   RPERKINS                  650.505.4876         1999-12-19  SH_CLERK      2500.00                       122            50
        192 Sarah                Bell                      SBELL                     650.501.1876         1996-02-04  SH_CLERK      4000.00                       123            50
EMPLOYEE_ID FIRST_NAME           LAST_NAME                 EMAIL                     PHONE_NUMBER         HIRE_DATE   JOB_ID         SALARY COMMISSION_PCT MANAGER_ID DEPARTMENT_ID
----------- -------------------- ------------------------- ------------------------- -------------------- ----------- ---------- ---------- -------------- ---------- -------------
        193 Britney              Everett                   BEVERETT                  650.501.2876         1997-03-03  SH_CLERK      3900.00                       123            50
        194 Samuel               McCain                    SMCCAIN                   650.501.3876         1998-07-01  SH_CLERK      3200.00                       123            50
        195 Vance                Jones                     VJONES                    650.501.4876         1999-03-17  SH_CLERK      2800.00                       123            50
        196 Alana                Walsh                     AWALSH                    650.507.9811         1998-04-24  SH_CLERK      3100.00                       124            50
        197 Kevin                Feeney                    KFEENEY                   650.507.9822         1998-05-23  SH_CLERK      3000.00                       124            50
25 rows selected

5.找出收取佣金的员工的不同工作；

SQL> SELECT DISTINCT job_id FROM employees WHERE commission_pct IS NOT NULL;
JOB_ID
----------
SA_MAN
SA_REP

6.找出各月倒数第3天受雇的所有员工。

SELECT * FROM employees WHERE LAST_DAY(HIRE_DATE)-2=HIRE_DATE;

7.找出早于12年前受雇佣的员工；

如果要求年份，最准确的算法是使用总月数/12;

SQL> SELECT * FROM employees WHERE MONTHS_BETWEEN(SYSDATE,hire_date)/12>12;

8.以首字母大写的方式显示所有员工的姓名；

SQL> SELECT INITCAP(first_name) FROM employees;
INITCAP(FIRST_NAME)
--------------------
Ellen
Sundar
Mozhe
David
Hermann
Shelli
Amit
Elizabeth
Sarah
David
Laura
Harrison
Alexis
Anthony
Gerald
Nanette
John
Kelly
Karen
Curtis

9.显示正好为5个字符的员工的姓名；

SQL> SELECT first_name FROM employees WHERE LENGTH(first_name)=5;
FIRST_NAME
--------------------
Ellen
Mozhe
David
Sarah
David
Laura
Kelly
Karen
Julia
Bruce
Kevin
Nancy
Peter
Vance
Payam
Neena
James
David
Diana
Jason

10.显示不带有“R”的员工的姓名；

SQL> SELECT * FROM employees WHERE first_name NOT LIKE '%R%';

11，显示所有员工姓名的前3个字符；

SQL> SELECT SUBSTR(first_name,0,3) FROM employees;
SUBSTR(FIRST_NAME,0,3)
----------------------
Ell
Sun
Moz
Dav
Her
She
Ami
Eli
Sar
Dav
Lau
Har
Ale
Ant
Ger
Nan
Joh
Kel
Kar
Cur

12.显示所有员工的姓名，用“a”替换所有“A”；

SQL> SELECT REPLACE(first_name,'A','a') FROM employees;
REPLACE(FIRST_NAME,'A','A')
---------------------------
Ellen
Sundar
Mozhe
David
Hermann
Shelli
amit
Elizabeth
Sarah
David
Laura
Harrison
alexis
anthony
Gerald
Nanette
John
Kelly
Karen
Curtis

13.显示员工的详细信息，按姓名排序；

SQL> SELECT * FROM employees ORDER BY first_name;

14.显示员工的姓名和雇佣的日期，根据其服务年限，将最老的员工排在最前面；

SQL> SELECT first_name,hire_date FROM employees ORDER BY hire_date;
FIRST_NAME           HIRE_DATE
-------------------- -----------
Steven               1987-06-17
Jennifer             1987-09-17
Neena                1989-09-21
Alexander            1990-01-03
Bruce                1991-05-21
Lex                  1993-01-13
Susan                1994-06-07
Hermann              1994-06-07
Shelley              1994-06-07
William              1994-06-07
Daniel               1994-08-16
Nancy                1994-08-17
Den                  1994-12-07
Payam                1995-05-01
Alexander            1995-05-18
Renske               1995-07-14
Trenna               1995-10-17
Nandita              1996-01-27
Janette              1996-01-30
Sarah                1996-02-04

15.显示所有员工的姓名、工作和工资，按工作的降序排序，若工作相同则按照工资排序；

SQL> SELECT first_name,job_id,salary FROM employees ORDER BY job_id DESC,salary;

16.显示所有员工姓名，加入公司的年份和月份，按受雇日期所在月排序，若月份相同则将最早年份的员工排在最前面。

需要从日期之中取出年份和月份，用TO_CHAR()函数完成。

SQL> SELECT first_name,TO_CHAR(hire_date,'yyyy') year,TO_CHAR(hire_date,'mm') months FROM employees ORDER BY months,year;

17.显示在（任何年份的）2月份首批的所有员工。

SQL> SELECT * FROM employees WHERE TO_CHAR(hire_date,'mm')=2;

18.显示姓名名字段的任何位置包含“A”的所有员工的姓名

SQL> SELECT first_name FROM employees WHERE first_name LIKE '%A%';
FIRST_NAME
--------------------
Amit
Alexis
Anthony
Alberto
Adam
Alexander
Alyssa
Alexander
Allan
Alana
10 rows selected

19.以年月日的方式显示所有员工的服务年限；

第1步：求出每个雇员的雇佣年数：被雇佣的总月数/12=年数；

SQL> SELECT first_name,hire_date,TRUNC(MONTHS_BETWEEN(SYSDATE,hire_date)/12) year FROM employees;

第2步：求出月数，以上计算之中被忽略的小数都是月份数，用MOD取即可；

SQL> SELECT first_name,hire_date,TRUNC(MONTHS_BETWEEN(SYSDATE,hire_date)/12) year, TRUNC(MOD(MONTHS_BETWEEN(SYSDATE,hire_date),12))FROM employees;

第3步：求出天数，最准的做法是在不超过30天的范围之内求;

现在已经知道当前的时间使用SYSDATE取出，而雇佣的日期使用hire_date取出，但是hire_date和SYSDATE之间的差距太大了，所以肯定会有误差，那么就必须想办法将hire_date的日期提升到和SYSDATE差距在30天的范围之内；

在之前学过2个函数：
MONTHS_BETWEEN():求出2个日期间的月份数，如果是：MONTHS_BETWEEN(SYSDATE,hire_date）求出的是雇佣日期到今天为止的雇佣月份数；

ADD_MONTHS():在一个日期上加上指定的月之后的日期，如果说hire_date + 与今天相距的月份数 = 一个新的日期数，且这个新的日期和SYSDATE就不超过30天了；

SQL> SELECT first_name,hire_date,
TRUNC(MONTHS_BETWEEN(SYSDATE,hire_date)/12) year,
TRUNC(MOD(MONTHS_BETWEEN(SYSDATE,hire_date),12)),
TRUNC(SYSDATE-ADD_MONTHS(hire_date,MONTHS_BETWEEN(SYSDATE,hire_date))) day
FROM employees;

本文出自 “strom的博客” 博客，谢绝转载！