sql系列(基础)-第二章 限制和排序数据

sql系列(基础)-第二章 限制和排序数据

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第二章 约束和排序数据

1. 在 emp 表中选择工资介于 1500 到 2500 的员工的信息;
注意:使用 between 下边界 and 上边界时。条件包括边界值;

SCOTT@ORCL>l       
  1  select * from emp
  2* where sal between 1500 and 2500
SCOTT@ORCL>/

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30

2. 在emp表中选择位于20,30 部门的员工的信息;

SCOTT@ORCL>select *from emp
  2  where deptno in (20,30);

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20
      7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20

11 rows selected.

3. 在emp表中选择位于员工的名字中包括大写字符 ‘A’ 的员工的信息;

SCOTT@ORCL>select * from emp
  2  where ename like '%A%';

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30

7 rows selected.
	
注意:假设查询的名字中包括%或者_ ,并且查询的时候又要查询这种信息,须要用到换位码。
注意:通配符%,表示0或者多个字符一样;通配符_,表示1个字符一样。

	3.1 创建与 emp 表结构同样的表;
SCOTT@ORCL>create table emp_n                    /* 參照emp表创建新表emp_n */
  2  as select * from emp where 1=2;           /* 加where 1=2 一致表结构没有数据 */

Table created.

SCOTT@ORCL>select * from emp_n;

no rows selected

	3.2 加入包括通配符的測试用数据;
SCOTT@ORCL>insert into emp_n(empno,ename,sal) values(&empno,&ename,&sal);
Enter value for empno: 1001
Enter value for ename: 'whwh%gogo'
Enter value for sal: 1000
old   1: insert into emp_n(empno,ename,sal) values(&empno,&ename,&sal)
new   1: insert into emp_n(empno,ename,sal) values(1001,'whwh%gogo',1000)

1 row created.

SCOTT@ORCL>/
Enter value for empno: 1002
Enter value for ename: '%whwh'
Enter value for sal: 2000
old   1: insert into emp_n(empno,ename,sal) values(&empno,&ename,&sal)
new   1: insert into emp_n(empno,ename,sal) values(1002,'%whwh',2000)

1 row created.

SCOTT@ORCL>/
Enter value for empno: 1003
Enter value for ename: 'whwh_gogo'
Enter value for sal: 3000
old   1: insert into emp_n(empno,ename,sal) values(&empno,&ename,&sal)
new   1: insert into emp_n(empno,ename,sal) values(1003,'whwh_gogo',3000)

1 row created.

SCOTT@ORCL>/
Enter value for empno: 1004
Enter value for ename: '_gogo'
Enter value for sal: 4000
old   1: insert into emp_n(empno,ename,sal) values(&empno,&ename,&sal)
new   1: insert into emp_n(empno,ename,sal) values(1004,'_gogo',4000)

1 row created.

SCOTT@ORCL>commit;

Commit complete.

SCOTT@ORCL>select * from emp_n;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      1001 whwh%gogo                                       1000
      1002 %whwh                                           2000
      1003 whwh_gogo                                       3000
      1004 _gogo                                           4000

	3.3 换位码的用法。(此处以\作为换位码。换位码还能够指定其它字符)
例:检索包括%的记录信息。
SCOTT@ORCL>select * from emp_n
  2  where ename like '%\%%' escape '\';

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      1001 whwh%gogo                                       1000
      1002 %whwh                                           2000

SCOTT@ORCL>select * from emp_n
  2  where ename like '%\%%';

no rows selected

例:检索以%开头的记录信息;
SCOTT@ORCL>select * from emp_n
  2  where ename like '\%%' escape '\';

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      1002 %whwh                                           2000

例:检索包括_的记录信息。
SCOTT@ORCL>select * from emp_n
  2  where ename like '%\_%' escape '\';

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      1003 whwh_gogo                                       3000
      1004 _gogo                                           4000

例:检索以_开头的记录信息;
SCOTT@ORCL>select * from emp_n
  2  where ename like '\_%' escape '\';

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      1004 _gogo                                           4000

4 复合条件的使用
	4.1 对于and条件的复合(能够将between...and...进行转换)
	
例:在emp表中选择工资介于2000到3000的员工的信息。
SCOTT@ORCL>select * from emp
  2  where sal>=2000 and sal<=3000;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20

SCOTT@ORCL>select * from emp
  2  where sal between 2000 and 3000;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20

	4.2 对于or条件复合(能够将in()进行转换)
例:在emp表中选择10号和20号部门的员工信息;
SCOTT@ORCL>select * from emp
  2  where deptno=10 or deptno=20;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10

8 rows selected.

SCOTT@ORCL>select * from emp
  2  where deptno in (10,20);

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10

8 rows selected.

	5 对于表中数据的排序
	5.1 asc  表示依照所给字段进行升序排列(默认升序)
		desc 表示依照所给字段进行降序排列
例:将emp表中10号部门的员工信息依照sal列升序排列
SCOTT@ORCL>select * from emp 
  2  where deptno=10;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10

SCOTT@ORCL>select * from emp
  2  where deptno=10
  3  order by sal asc;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7839 KING       PRESIDENT            17-NOV-81       5000                    10

SCOTT@ORCL>select * from emp
  2  where deptno=10
  3  order by sal;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7839 KING       PRESIDENT            17-NOV-81       5000                    10

例:将emp表中20号部门的员工信息依照sal列降序排列
SCOTT@ORCL>select * from emp
  2  where deptno=20
  3  order by sal desc;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20

	5.2 假设order by 后面跟多个字段。则将结果集先依照第1个字段进行排序【条件1】。
		再按第2个字段进行排序【条件2】;
	注意:【条件1】假设依照第1个字段分不开先后顺序的时候。才会依照第2个字段排序。
		   asc 或者desc 影响的字段,不过它紧挨着的那个字段。
例:将emp表中10号部门的员工信息按sal降序排列,empno升序排列;
SCOTT@ORCL>select * from emp
  2  where deptno=10
  3  order by sal desc,empno asc;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10

例:将emp表中20号部门的员工信息依照empno 降序排列,sal升序排列;
SCOTT@ORCL>select * from emp
  2  where deptno=20
  3  order by empno desc,sal asc;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20

	 5.3 除了能够使用字段排序。还能够使用字段所在的先后位置排序;
确定字段在表中的先后顺序。
SCOTT@ORCL>set lines 100
SCOTT@ORCL>desc emp;
 Name                                                  Null?

Type ----------------------------------------------------- -------- ------------------------------------ EMPNO NOT NULL NUMBER(4) ENAME VARCHAR2(10) JOB VARCHAR2(9) MGR NUMBER(4) HIREDATE DATE SAL NUMBER(7,2) COMM NUMBER(7,2) DEPTNO NUMBER(2) 例:将emp表中10号部门的员工信息按sal降序排列,empno升序排列。 SCOTT@ORCL>select * from emp 2 where deptno=10 3 order by 6 desc,1 asc; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO---------- ---------- --------- ---------- --------- ---------- ---------- ---------- 7839 KING PRESIDENT 17-NOV-81 5000 10 7782 CLARK MANAGER 7839 09-JUN-81 2450 10 7934 MILLER CLERK 7782 23-JAN-82 1300 10例:将emp表中20号部门的员工信息依照empno 降序排列,sal升序排列;SCOTT@ORCL>select * from emp 2 where deptno=20 3 order by 1 desc,6 asc; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO---------- ---------- --------- ---------- --------- ---------- ---------- ---------- 7902 FORD ANALYST 7566 03-DEC-81 3000 20 7876 ADAMS CLERK 7788 23-MAY-87 1100 20 7788 SCOTT ANALYST 7566 19-APR-87 3000 20 7566 JONES MANAGER 7839 02-APR-81 2975 20 7369 SMITH CLERK 7902 17-DEC-80 800 20 5.4 除了能够使用number 类型的字段进行排序外,还能够使用字符串或者时间类型的字段进行排序。 注意:字符串排序:依照字符相应的ASCII码的先后进行排序。 日期排序:依照日期的先后进行排序,时间越往后越大;例:将emp表中员工依照job升序、ename降序进行排列;(先按Job排序。同样的job按ename降序)SCOTT@ORCL>select * from emp 2 order by job asc,ename desc; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO---------- ---------- --------- ---------- --------- ---------- ---------- ---------- 7788 SCOTT ANALYST 7566 19-APR-87 3000 20 7902 FORD ANALYST 7566 03-DEC-81 3000 20 7369 SMITH CLERK 7902 17-DEC-80 800 20 7934 MILLER CLERK 7782 23-JAN-82 1300 10 7900 JAMES CLERK 7698 03-DEC-81 950 30 7876 ADAMS CLERK 7788 23-MAY-87 1100 20 7566 JONES MANAGER 7839 02-APR-81 2975 20 7782 CLARK MANAGER 7839 09-JUN-81 2450 10 7698 BLAKE MANAGER 7839 01-MAY-81 2850 30 7839 KING PRESIDENT 17-NOV-81 5000 10 7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30 7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30 7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30 7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 3014 rows selected.例:将emp表中员工依照 HIREDATE 升序,sal降序排列(假设HIREDATE同样,依照sal降序)先将HIREDATE显示格式设定SCOTT@ORCL>alter session set nls_date_format='yyyy-mm-dd';Session altered.SCOTT@ORCL>select * from emp 2 order by hiredate asc,sal desc; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO---------- ---------- --------- ---------- ---------- ---------- ---------- ---------- 7369 SMITH CLERK 7902 1980-12-17 800 20 7499 ALLEN SALESMAN 7698 1981-02-20 1600 300 30 7521 WARD SALESMAN 7698 1981-02-22 1250 500 30 7566 JONES MANAGER 7839 1981-04-02 2975 20 7698 BLAKE MANAGER 7839 1981-05-01 2850 30 7782 CLARK MANAGER 7839 1981-06-09 2450 10 7844 TURNER SALESMAN 7698 1981-09-08 1500 0 30 7654 MARTIN SALESMAN 7698 1981-09-28 1250 1400 30 7839 KING PRESIDENT 1981-11-17 5000 10 7902 FORD ANALYST 7566 1981-12-03 3000 20 7900 JAMES CLERK 7698 1981-12-03 950 30 7934 MILLER CLERK 7782 1982-01-23 1300 10 7788 SCOTT ANALYST 7566 1987-04-19 3000 20 7876 ADAMS CLERK 7788 1987-05-23 1100 2014 rows selected. 6. 使用结果集中的别名进行排序。例:依照emp表中员工对于的年薪(sal*12)进行排序。SCOTT@ORCL>select empno,ename,hiredate,sal*12 year_sal 2 from emp 3 order by year_sal desc; EMPNO ENAME HIREDATE YEAR_SAL---------- ---------- ---------- ---------- 7839 KING 1981-11-17 60000 7902 FORD 1981-12-03 36000 7788 SCOTT 1987-04-19 36000 7566 JONES 1981-04-02 35700 7698 BLAKE 1981-05-01 34200 7782 CLARK 1981-06-09 29400 7499 ALLEN 1981-02-20 19200 7844 TURNER 1981-09-08 18000 7934 MILLER 1982-01-23 15600 7521 WARD 1981-02-22 15000 7654 MARTIN 1981-09-28 15000 7876 ADAMS 1987-05-23 13200 7900 JAMES 1981-12-03 11400 7369 SMITH 1980-12-17 960014 rows selected.注意:当然也能够依照字符串、日期相应的别名进行排序; 7. 假设排序的字段中包括null值,结果会怎么样? 注意:在字段进行比較大小的时候,null 值比不论什么值都大;例:emp表中员工的信息依照comm降序排列;SCOTT@ORCL>select * from emp 2 order by comm desc; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO---------- ---------- --------- ---------- ---------- ---------- ---------- ---------- 7369 SMITH CLERK 7902 1980-12-17 800 20 7782 CLARK MANAGER 7839 1981-06-09 2450 10 7902 FORD ANALYST 7566 1981-12-03 3000 20 7900 JAMES CLERK 7698 1981-12-03 950 30 7876 ADAMS CLERK 7788 1987-05-23 1100 20 7566 JONES MANAGER 7839 1981-04-02 2975 20 7698 BLAKE MANAGER 7839 1981-05-01 2850 30 7934 MILLER CLERK 7782 1982-01-23 1300 10 7788 SCOTT ANALYST 7566 1987-04-19 3000 20 7839 KING PRESIDENT 1981-11-17 5000 10 7654 MARTIN SALESMAN 7698 1981-09-28 1250 1400 30 7521 WARD SALESMAN 7698 1981-02-22 1250 500 30 7499 ALLEN SALESMAN 7698 1981-02-20 1600 300 30 7844 TURNER SALESMAN 7698 1981-09-08 1500 0 3014 rows selected.注意:null 值之间的排序不考虑(由于Null 和 null 之间无法比較大小)假设我想将comm有值的部分换到上面,该怎么办?SCOTT@ORCL>select * from emp 2 order by comm desc nulls last; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO---------- ---------- --------- ---------- ---------- ---------- ---------- ---------- 7654 MARTIN SALESMAN 7698 1981-09-28 1250 1400 30 7521 WARD SALESMAN 7698 1981-02-22 1250 500 30 7499 ALLEN SALESMAN 7698 1981-02-20 1600 300 30 7844 TURNER SALESMAN 7698 1981-09-08 1500 0 30 7788 SCOTT ANALYST 7566 1987-04-19 3000 20 7839 KING PRESIDENT 1981-11-17 5000 10 7876 ADAMS CLERK 7788 1987-05-23 1100 20 7900 JAMES CLERK 7698 1981-12-03 950 30 7902 FORD ANALYST 7566 1981-12-03 3000 20 7934 MILLER CLERK 7782 1982-01-23 1300 10 7698 BLAKE MANAGER 7839 1981-05-01 2850 30 7566 JONES MANAGER 7839 1981-04-02 2975 20 7369 SMITH CLERK 7902 1980-12-17 800 20 7782 CLARK MANAGER 7839 1981-06-09 2450 1014 rows selected.同理:自己验证 升序 排列SCOTT@ORCL>select * from emp 2 order by comm asc nulls first;</span>




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