SQL 基础之where过滤和 运算符（五）

使用WHERE子句，将不满足条件的行过滤掉:

WHERE过滤的注意事项：

WHERE子句紧随FROM子句。

WHERE子句后跟条件表达式

列名、表达式、常量

比较运算符：=, <=, BETWEEN, IN, LIKE, 和 NULL

–逻辑运算符： AND, OR和 NOT

替代变量

DEFINE 和 VERIFY 命令

文字值

WHERE子句后不能跟列别名

语法如下：

SELECT *|{[DISTINCT] column|expression [alias],...}

FROM table

[WHERE condition(s)];

1、比如现在查找一下部门ID为90的部门里面有哪些员工

select last_name,department_id from employees  where department_id = 90;

2、查找部门ID 为100的人员信息，如：姓名、员工编号等

select first_name,employee_id,job_id,department_id  from employees where department_id = 100;

3、当条件为字符和日期要包含在单引号中。

字符大小写敏感，日期格式敏感。

默认的日期格式是 DD-MON-RR

3.1 查找last_name为Whalen的员工departmen id等信息

select last_name,job_id,department_id from employees where last_name = 'Whalen';

3.2 查找入职日期为07年12月19日的员工first_name 和部门ID

select first_name,department_id,hire_date from employees where hire_date = '19-DEC-07';

4、比较运算符

4.1 查找一下工资小于2800 的员工的名字和部门id号

select last_name,department_id,salary from employees where salary < 2800 order by salary;

4.2 查找一下工资大于等于3000 的员工 的名字和job_id,并采用升序排列

select last_name,job_id,salary from employees where salary>=3000 orader by salary;

4.3 查找一下工资大于等于10000的员工姓名，并按照 xxx 's salary is 10000的格式输入

select first_name||q'['s salary is ]' || salary as "salary is 10000 of emp" 

from employees 

where salary=10000;

4.4  查找一下工资在8000-10000之间的员工姓名和员工id

select employee_id,first_name,salary from employees where  salary between 8000 and 10000 order by salary;

4.5 查找一下工资为7000、3100、8100、9000、10000的员工名字

select first_name,salary from employees where salary in(7000,3100,8000,9000,10000);

4.6 查找员工名称为S开头的job_id 

select first_name,job_id from employees where first_name like 'S%';

4.7 查找员工名称中带有s的 job_id

select first_name,job_id from employees where first_name like '%s';

4.8 查找名字第二个字母是o的员工信息

select first_name,job_id from employees where first_name like '_o%';

4.9 查找名字第三个字母为e和a的员工名字

select employee_id,last_name,salary,department_id from employees where manager_id= &mgr_num order by &order_col

4.9.1 查找manager_id 为空的名字

select  first_name,manager_id  from employees where manager_id is null;

4.9.2 查找到04年入职的员工姓名

select last_name,hire_date from employees where hire_date like '%04';

5、逻辑运算符

5.1、查找工资大于10000并且 job_id 含有MAN的员工信息

select first_name,employee_id,salary from employees where salary>=1000 and  job_id like '%MAN%';

5.2、查找工资大于等于10000 或者job_id 含有MAN的员工 的名字和employee_id

select first_name,employee_id,job_id,salary from employees where salary>=10000  or  job_id  like '%MAN%';

5.3 查找job_id  不在'HR_EMP','ST_MAN','ST_CLERK' 这工作id里面的员工名字和job_id

select last_name,job_id from employees  where job_id not in('HR_EMP','ST_MAN','ST_CLERK');

5.4  列出工资不在 5000-12000 范围的员工的姓名和工资

sql >select last_name,salary from employees where salary not between 5000 and 12000 order by salary;

LAST_NAME      SALARY

------------------------- ----------

Olson2100

Philtanker2200

Markle2200

Landry2400

Gee       2400

Vargas2500

Patel2500

Colmenares2500

Marlow2500

Sullivan       2500

Perkins        2500

OConnell       2600

Grant2600

Matos2600

Himuro2600

Mikkilineni2700

Seo        2700

Atkinson       2800

Geoni2800

Tobias2800

Jones2800

Rogers2900

Baida2900

Gates2900

Feeney3000

Cabrio3000

Walsh3100

Fleaur3100

Khoo3100

Davies3100

Stiles3200

Nayer3200

Taylor3200

McCain3200

Bissot3300

Mallin3300

Dellinger        3400

Rajs        3500

Dilly        3600

Ladwig3600

Chung3800

Everett         3900

Bell        4000

Bull        4100

Sarchand        4200

Lorentz         4200

Whalen4400

Pataballa        4800

Austin4800

Higgins                 12008

Greenberg       12008

Hartstein               13000

Partners               13500

Russell                14000

De Haan                17000

Kochhar                17000

King               24000

57 rows selected.

6、优先级（可以使用括号改变优先级顺序）

1、查找部门为SA_REP或者AD_PRES部门里面工资大于15000的员工名字、job_id、工资等信息

SELECT last_name, job_id, salary FROM employees WHERE job_id = 'SA_REP' OR job_id = 'AD_PRES' AND salary > 15000;

2、查找job_id 为SA_REP或者AD_PRES部门里面工资大于15000的员工姓名、job_id

SELECT last_name, job_id, salary FROM employees WHERE (job_id = 'SA_REP' OR job_id = 'AD_PRES') AND salary > 15000;

3、列出工资不在 5000-12000,部门在 20 或 50 的员工的姓名和工资

select last_name,department_id,salary from employees where salary not between 5000 and 12000 and department_id=20 or department_id=50;

 或

select last_name,department_id,salary from employees where salary not between 5000 and 12000 and department_id in(20,50);