sql系列（基础篇）-第二章约束和排序数据(三)
300 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号部门的员工信息按照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 如果order by 后面跟多个字段，则将结果集先按照第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】如果按照第1个字段分不开先后顺序的时候，才会按照第2个字段排序；
asc 或者desc 影响的字段，仅仅是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号部门的员工信息按照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 除了可以使用字段排序，还可以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号部门的员工信息按照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 除了可以使用number 类型的字段进行排序外，还可以使用字符串或