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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 30 14 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 20 14 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 9600 14 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 30 14 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 10 14 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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