使用sql语句实现表的分页显示--实用--面试官最喜欢问的考题

Oracle 版本 Release 10.2.0.4.0 系统平台 linux 5.0 企业版
以oracle自带的emp表为例
注意：如果装完后没有emp表，可以执行下面脚本安装
SQL> @/u02/app/oracle/product/10.2.0/db2/rdbms/admin/utlsampl.sql
执行完后emp表就装上了，默认用户名和密码：scott/tiger.如果不知道密码可以更改
SQL> show user
USER is "SYS"
SQL> alter user scott identified by "123";
用户名为scott，密码为123
如果提示被锁，执行下面的命令
SQL>alter user scott account unlock;
SQL> conn scott/123
Connected.
SQL> 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)
查看表内容，并以empno顺序排列，由大到小
SQL> select * from emp order by empno desc;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7934 MILLER CLERK 7782 23-JAN-82 1300 10
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7839 KING PRESIDENT 17-NOV-81 5000 10
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7566 JONES MANAGER 7839 02-APR-81 2975 20
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7369 SMITH CLERK 7902 17-DEC-80 800 20
14 rows selected.
以实现员工号empno分页显示为例，总共14行，一页5行，共3页。（几页自己定）
[align=left]第一页： 第二页： 第三页：[/align]
[align=left]7934 7839 7566
7902 7788 7521
7900 7782 7499
7876 7698 7369
7844 7654[/align]
[align=left]1.显示第一页的内容：[/align]
[align=left]SQL> select * from (select a.*,rownum rn from (select * from emp order by empno desc) a where rownum<=5) where rn>=1;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO RN
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7934 MILLER CLERK 7782 23-JAN-82 1300 10 1
7902 FORD ANALYST 7566 03-DEC-81 3000 20 2
7900 JAMES CLERK 7698 03-DEC-81 950 30 3
7876 ADAMS CLERK 7788 23-MAY-87 1100 20 4
7844 URNER SALESMAN 7698 08-SEP-81 1500 0 30 5
2.显示第二页的内容
SQL> select * from (select a.*,rownum rn from (select * from emp order by empno desc) a where rownum<=10) where rn>=6;[/align]
[align=left]EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO RN
---------- ---------- --------- ---------- --------- ---------- ---------- ---------- -----
7839 KING PRESIDENT 17-NOV-81 5000 10 6
7788 SCOTT ANALYST 7566 19-APR-87 3000 20 7
7782 CLARK MANAGER 7839 09-JUN-81 2450 10 8
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30 9
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30 10
3.显示第三页内容[/align]
[align=left]SQL> select * from (select a.*,rownum rn from (select * from emp order by empno desc) a where rownum<=14) where rn>=11;[/align]
[align=left]EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO RN
---------- ---------- --------- ---------- --------- ---------- ---------- ---------- ------
7566 JONES MANAGER 7839 02-APR-81 2975 20 11
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30 12
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30 13
7369 SMITH CLERK 7902 17-DEC-80 800 20 14
这样就设置就达到了分三页显示内容的目的。一些论坛上和网站上的分页显示内容就是基于sql语句来实现的。[/align]
[align=left]当然，其中的数字我们可以使用替代符&来替代，这样当我们执行语句的时候就不用一条一条的输入了，例如：[/align]
[align=left]SQL> select * from (select a.*,rownum rn from (select * from emp order by empno desc) a where rownum<=&max) where rn>=&min;
Enter value for max: 10
Enter value for min: 6
old 1: select * from (select a.*,rownum rn from (select * from emp order by empno desc) a where rownum<=&max) where rn>=&min
new 1: select * from (select a.*,rownum rn from (select * from emp order by empno desc) a where rownum<=10) where rn>=6[/align]
[align=left]EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO RN
---------- ---------- --------- ---------- --------- ---------- ---------- ---------- ------
7839 KING PRESIDENT 17-NOV-81 5000 10 6
7788 SCOTT ANALYST 7566 19-APR-87 3000 20 7
7782 CLARK MANAGER 7839 09-JUN-81 2450 10 8
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30 9
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30 10[/align]
[align=left]如果要执行第二条时，如下：[/align]
[align=left]SQL> /
Enter value for max: 5
Enter value for min: 1
old 1: select * from (select a.*,rownum rn from (select * from emp order by empno desc) a where rownum<=&max) where rn>=&min
new 1: select * from (select a.*,rownum rn from (select * from emp order by empno desc) a where rownum<=5) where rn>=1[/align]
[align=left]EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO RN
---------- ---------- --------- ---------- --------- ---------- ---------- ---------- ------
7934 MILLER CLERK 7782 23-JAN-82 1300 10 1
7902 FORD ANALYST 7566 03-DEC-81 3000 20 2
7900 JAMES CLERK 7698 03-DEC-81 950 30 3
7876 ADAMS CLERK 7788 23-MAY-87 1100 20 4
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30 5[/align]
[align=left]注意：上面的a为定义的别名，可以为任意字符,rn可以为任意字符[/align]
[align=left]rownum为表中的一个伪字段，我们同样可以查询，例如[/align]



[align=left]一个简单的分页显示就到这里了。 [/align]
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