子查询

范例1：查询公司之中工资最低的雇员的完整信息

SELECT MIN(sal) FROM emp ;

SELECT *

FROM emp

WHERE sal=(

    SELECT MIN(sal) FROM emp) ;

 

范例2：子查询返回的结果就当它是一个数字，即，直接判断此数字

SELECT *

FROM emp

WHERE sal=800 ;  è 子查询返回的只是一个数字：800

 

范例3：查询出基本工资比ALLEN低的全部雇员信息

SELECT sal FROM emp WHERE ename='ALLEN' ;

SELECT *

FROM emp

WHERE sal< (

    SELECT sal

    FROM emp

    WHERE ename='ALLEN') ;

范例4：查询基本工资高于公司平均薪金的全部雇员信息

SELECT AVG(sal) FROM emp ;

SELECT *

FROM emp

WHERE sal>(

    SELECT AVG(sal)

    FROM emp) ;

范例5：查找出与ALLEN从事同一工作，并且基本工资高于雇员编号为7521的全部雇员信息

SELECT job FROM emp WHERE ename='ALLEN'

SELECT sal FROM emp WHERE empno=7521 ;

SELECT *

FROM emp

WHERE job=(

        SELECT job

        FROM emp

        WHERE ename='ALLEN')

      AND

    sal>(

      SELECT sal

      FROM emp

      WHERE empno=7521) ;

范例6：查询与SCOTT从事同一工作且工资相同的雇员信息

SELECT job,sal

FROM emp

WHERE ename='SCOTT' ;

SELECT *

FROM emp

WHERE (job,sal)=(

    SELECT job,sal

    FROM emp

    WHERE ename='SCOTT') ;

SELECT *

FROM emp

WHERE (job,sal)=(

    SELECT job,sal

    FROM emp

    WHERE ename='SCOTT') AND ename<>'SCOTT' ;

范例7：查询与雇员7566从事同一工作且领导相同的全部雇员信息

SELECT job , mgr FROM emp WHERE empno=7566 ;

SELECT *

FROM emp

WHERE (job,mgr)=(

    SELECT job , mgr

    FROM emp

    WHERE empno=7566) ;

步骤三：增加一个过滤条件，不显示7566的信息

SELECT * FROM emp

WHERE ( job,mgr)=(

        SELECT job,mgr

        FROM emp

        WHERE empno=7566)

    AND empno<>7566 ;

 

范例8：查询与ALLEN从事同一工作且在同一年雇佣的全部雇员信息（包括ALLEN）

SELECT job, TO_CHAR(hiredate, 'yyyy')

FROM emp

WHERE ename='ALLEN' ;

SELECT *

FROM emp

WHERE (job, TO_CHAR(hiredate, 'yyyy'))=(

    SELECT job, TO_CHAR(hiredate, 'yyyy')

    FROM emp

    WHERE ename='ALLEN') ;

范例9：查询出与每个部门中最低工资相同的全部雇员信息

SELECT MIN(sal)

FROM emp

GROUP BY deptno ;

SELECT *

FROM emp

WHERE sal IN (

      SELECT MIN(sal)

      FROM emp

      GROUP BY deptno) ;

 

范例10：查询出不与每个部门中最低工资相同的全部雇员信息

SELECT *

FROM emp

WHERE sal NOT IN (

      SELECT MIN(sal)

      FROM emp

      GROUP BY deptno) ;

 

范例11：观察null对NOT IN操作的影响

SELECT e.ename

FROM emp e

WHERE e.empno NOT IN (

      SELECT m.mgr

      FROM emp m) ;

范例12：列出每个部门经理的工资

SELECT MIN(sal)

FROM emp

WHERE job='MANAGER'

GROUP BY deptno ;

 

范例13：使用=ANY操作符完成查询

SELECT * FROM emp

WHERE sal=ANY (

      SELECT MIN(sal)

      FROM emp

      WHERE job='MANAGER'

      GROUP BY deptno) ;

 

范例14：使用>ANY操作符完成查询

SELECT * FROM emp

WHERE sal >ANY (

      SELECT MIN(sal)

      FROM emp

      WHERE job='MANAGER'

      GROUP BY deptno) ;

 

范例15：使用<ANY操作符完成查询

SELECT * FROM emp

WHERE sal <ANY (

      SELECT MIN(sal)

      FROM emp

      WHERE job='MANAGER'

      GROUP BY deptno) ;

 

范例17：使用<>ALL操作符完成查询

SELECT * FROM emp

WHERE sal <>ALL (

      SELECT MIN(sal)

      FROM emp

      WHERE job='MANAGER'

      GROUP BY deptno) ;

 

范例18：验证exists结构

SELECT * FROM emp

WHERE EXISTS(

  SELECT * FROM emp WHERE empno=9999) ;

范例19：验证exists结构

SELECT * FROM emp

WHERE EXISTS(

  SELECT * FROM emp) ;

 

范例20：使用NOT EXISTS

SELECT * FROM emp

WHERE NOT EXISTS(

(SELECT * FROM emp WHERE empno=9999));

 

范例21：查询部门编号、雇员人数、平均工资，并且要求这些部门的平均工资高于公司平均薪金

SELECT AVG(sal) FROM emp ;

SELECT deptno, COUNT(empno), AVG(sal)

FROM emp

GROUP BY deptno ;

SELECT deptno, COUNT(empno), AVG(sal)

FROM emp

GROUP BY deptno

HAVING AVG(sal)>(

    SELECT AVG(sal)

    FROM emp);

范例22：查询出每个部门平均工资最高的部门名称及平均工资

SELECT MAX(AVG(sal))

FROM emp

GROUP BY deptno ;

SELECT d.dname, ROUND(AVG(e.sal),2)

FROM emp e ,dept d

WHERE e.deptno=d.deptno

GROUP BY d.dname

HAVING AVG(sal)=(

      SELECT MAX(AVG(sal))

      FROM emp

      GROUP BY deptno) ;

 

范例23：要求查询出每个部门的编号、名称、位置、部门人数、平均工资

SELECT *

FROM dept ;

SELECT deptno dno, COUNT(empno) count , ROUND(AVG(sal),2) avg

FROM emp

GROUP BY deptno ;

SELECT d.deptno,d.dname,d.loc,temp.count,temp.avg

FROM dept d, (SELECT deptno dno, COUNT(empno) count , ROUND(AVG(sal),2) avg

            FROM emp

            GROUP BY deptno) temp

WHERE d.deptno=temp.dno(+) ;

 

范例24：利用多字段分组

SELECT d.deptno,d.dname,d.loc,COUNT(e.empno) count,ROUND(AVG(sal),2) avg

FROM emp e,dept d

WHERE e.deptno(+)=d.deptno

GROUP BY d.deptno,d.dname,d.loc ;

范例25：查询出所有在部门“SALES”（销售部）工作的员工的编号、姓名、基本工资、奖金、职位、雇佣日期、部门的最高和最低工资。

SELECT deptno FROM dept WHERE dname='SALES' ;

SELECT empno ,ename ,sal ,comm ,job ,hiredate

FROM emp

WHERE deptno=(

      SELECT deptno

      FROM dept

      WHERE dname='SALES') ;

SELECT e.empno, e.ename, e.sal, e.comm, e.job ,e.hiredate , temp.max ,temp.min

FROM emp e , (

    SELECT deptno dno , MAX(sal) max , MIN(sal) min

    FROM emp

    GROUP BY deptno) temp  è  子查询负责统计信息，使用temp表示临时表的统计结果

WHERE e.deptno=(

      SELECT deptno

      FROM dept

      WHERE dname='SALES')

      AND e.deptno=temp.dno ;

 

范例26：查询出所有薪金高于公司平均薪金的员工编号、姓名、基本工资、职位、雇佣日期，所在部门名称、位置，上级领导姓名，公司的工资等级，部门人数、平均工资、平均服务年限。

SELECT AVG(sal) FROM emp ;

SELECT e.empno, e.ename, e.sal, e.job, e.hiredate

FROM emp e

WHERE e.sal>(

      SELECT AVG(sal)

      FROM emp) ;

SELECT e.empno, e.ename, e.sal, e.job, e.hiredate, d.dname, d.loc

FROM emp e , dept d

WHERE e.sal>(

      SELECT AVG(sal)

      FROM emp)

      AND e.deptno=d.deptno ;

SELECT e.empno, e.ename, e.sal, e.job, e.hiredate, d.dname, d.loc, m.ename mname

FROM emp e , dept d , emp m

WHERE e.sal>(

      SELECT AVG(sal)

      FROM emp)

      AND e.deptno=d.deptno

      AND e.mgr=m.empno(+);

SELECT e.empno, e.ename, e.sal, e.job, e.hiredate, d.dname, d.loc, m.ename mname , s.grade

FROM emp e , dept d , emp m ,salgrade s

WHERE e.sal>(

      SELECT AVG(sal)

      FROM emp)

      AND e.deptno=d.deptno

      AND e.mgr=m.empno(+)

      AND e.sal BETWEEN s.losal AND s.hisal ;

SELECT  e.empno, e.ename, e.sal, e.job, e.hiredate, d.dname, d.loc, m.ename mname , s.grade ,

        temp.count, temp.avg , temp.avgyear

FROM emp e , dept d , emp m ,salgrade s ,(

SELECT deptno dno, COUNT(empno) count ,

     ROUND(AVG(sal),2) avg , ROUND(AVG(MONTHS_BETWEEN(SYSDATE,hiredate)/12),2) avgyear

    FROM emp

    GROUP BY deptno) temp

WHERE e.sal>(

      SELECT AVG(sal)

      FROM emp)

      AND e.deptno=d.deptno

      AND e.mgr=m.empno(+)

      AND e.sal BETWEEN s.losal AND s.hisal

      AND e.deptno=temp.dno;

 

范例27：列出薪金比“ALLEN”或“CLARK”多的所有员工的编号、姓名、基本工资、部门名称、其领导姓名，部门人数。

SELECT sal FROM emp WHERE ename IN ('ALLEN' , 'CLARK') ;

SELECT e.empno, e.ename, e.sal

FROM emp e

WHERE e.sal >ANY(

      SELECT sal

      FROM emp

      WHERE ename IN ('ALLEN' , 'CLARK'))

      AND e.ename NOT IN('ALLEN','CLARK');

SELECT e.empno ,e.ename , e.sal , d.dname

FROM emp e , dept d

WHERE e.sal>ANY(

  SELECT sal

  FROM emp

  WHERE ename IN('ALLEN','CLARK'))

  AND e.ename NOT IN('ALLEN','CLARK')

  AND e.deptno=d.deptno ;

SELECT e.empno ,e.ename , e.sal , d.dname,m.ename mname

FROM emp e , dept d , emp m

WHERE e.sal>ANY(

  SELECT sal

  FROM emp

  WHERE ename IN('ALLEN','CLARK'))

  AND e.ename NOT IN('ALLEN','CLARK')

  AND e.deptno=d.deptno

  AND e.mgr=m.empno(+);

SELECT e.empno ,e.ename , e.sal , d.dname,m.ename mname,temp.count

FROM emp e , dept d , emp m , (

  SELECT deptno dno , COUNT(empno) count

  FROM emp

  GROUP BY deptno) temp

WHERE e.sal>ANY(

  SELECT sal

  FROM emp

  WHERE ename IN('ALLEN','CLARK'))

  AND e.ename NOT IN('ALLEN','CLARK')

  AND e.deptno=d.deptno

  AND e.mgr=m.empno(+)

  AND e.deptno=temp.dno ;

 

范例28：列出公司各个部门的经理（假设每个部门只有一个经理，job为“MANAGER”）的姓名、薪金、部门名称、部门人数、部门平均工资。

SELECT ename, sal

FROM emp

WHERE job='MANAGER' ;

SELECT e.ename, e.sal, d.dname

FROM emp e, dept d

WHERE job='MANAGER'

      AND e.deptno=d.deptno ;

SELECT e.ename, e.sal, d.dname , temp.count , temp.avg

FROM emp e, dept d , (

      SELECT deptno dno , COUNT(empno) count , ROUND(AVG(sal),2) avg

      FROM emp

      GROUP BY deptno) temp

WHERE job='MANAGER'

      AND e.deptno=d.deptno

      AND e.deptno=temp.dno ;

范例29：查询出公司每个部门的编号、名称、位置、部门人数、平均工资

SELECT deptno , dname , loc ,

  (SELECT COUNT(empno) FROM emp WHERE deptno=d.deptno) count ,

  (SELECT AVG(sal) FROM emp WHERE deptno=d.deptno) avg

FROM dept d ;

范例30：使用WITH子句将emp表中的数据定义为临时表

WITH e AS (

    SELECT * FROM emp)

SELECT *

FROM e ;

 

范例31：查询每个部门的编号、名称、位置、部门平均工资、人数

WITH e AS (

    SELECT deptno dno , ROUND(AVG(sal),2) avg , COUNT(sal) count

    FROM emp

    GROUP BY deptno)

SELECT d.deptno,d.dname,d.loc,e.count,e.avg

FROM e , dept d

WHERE e.dno(+)=d.deptno ;

 

范例32：查询每个部门工资最高的雇员编号、姓名、职位、雇佣日期、工资、部门编号、部门名称，显示的结果按照部门编号进行排序

WITH e AS (

    SELECT deptno dno , MAX(sal) max

    FROM emp

    GROUP BY deptno)

SELECT em.empno , em.ename , em.job , em.hiredate , em.sal , d.deptno,d.dname

FROM e , emp em , dept d

WHERE e.dno=em.deptno AND em.sal=e.max AND e.dno=d.deptno

ORDER BY em.deptno ;

 

范例26：使用PARTITION子句

SELECT deptno , ename, sal ,

    SUM(sal) OVER (PARTITION BY deptno) sum

FROM emp ;

 

范例27：不使用PARTITION进行分区，直接利用OVER子句操作

SELECT deptno , ename, sal ,

    SUM(sal) OVER () sum

FROM emp ;

 

范例28：通过PARTITION设置多个分区字段

SELECT deptno , ename, sal , job ,

      SUM(sal) OVER (PARTITION BY deptno , job) sum

FROM emp ;

 

范例29：观察ORDER BY子句

SELECT deptno , ename, sal ,

      RANK() OVER (PARTITION BY deptno ORDER BY sal DESC) rk

FROM emp ;

 

范例30：设置多个排序字段（sal和hiredate）

SELECT deptno , ename, sal , hiredate ,

      RANK() OVER (PARTITION BY deptno ORDER BY sal , hiredate DESC) rk

FROM emp ;

 

范例31：直接利用ORDER BY排序所有数据

SELECT deptno , ename, sal , hiredate ,

      SUM(sal) OVER (ORDER BY ename DESC) SUM

FROM emp ;

 

范例32：使用NULLS LAST

SELECT deptno , ename, sal , comm ,

      RANK() OVER (ORDER BY comm DESC NULLS LAST) rk ,

      SUM(sal) OVER (ORDER BY comm DESC NULLS LAST) SUM

FROM emp ;

 

范例33：在sal上设置偏移量

SELECT deptno , ename, sal ,

      SUM(sal) OVER (PARTITION BY deptno ORDER BY sal RANGE 300 PRECEDING) sum

FROM emp ;

 

范例34：设置偏移量为300，采用下匹配方式处理

SELECT deptno , ename, sal ,

      SUM(sal) OVER (PARTITION BY deptno ORDER BY sal RANGE BETWEEN 0 PRECEDING AND 300 FOLLOWING) sum

FROM emp ;

 

范例35：匹配当前行数据

SELECT deptno , ename, sal ,

      SUM(sal) OVER (PARTITION BY deptno ORDER BY sal RANGE BETWEEN 0 PRECEDING AND CURRENT ROW) sum

FROM emp ;

 

范例36：使用UNBOUNDED不设置边界

SELECT deptno , ename, sal ,

      SUM(sal) OVER (PARTITION BY deptno ORDER BY sal RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) sum

FROM emp ;

 

范例37：设置2行物理偏移

SELECT deptno , ename, sal ,

      SUM(sal) OVER (PARTITION BY deptno ORDER BY sal ROWS 2 PRECEDING) sum

FROM emp ;

 

范例38：设置查询行范围

SELECT deptno , ename, sal ,

      SUM(sal) OVER (PARTITION BY deptno ORDER BY sal ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) sum

FROM emp ;

范例39：查询雇员编号是7369的雇员姓名、职位、基本工资、部门编号、部门的人数、平均工资、最高工资、最低工资、总工资

SELECT *

FROM (

SELECT empno,ename,job,sal,deptno ,

COUNT(empno) OVER (PARTITION BY deptno) count ,

ROUND(AVG(sal) OVER (PARTITION BY deptno)) avg ,

SUM(sal) OVER (PARTITION BY deptno) sum ,

MAX(sal) OVER (PARTITION BY deptno) max ,

MIN(sal) OVER (PARTITION BY deptno) min

FROM emp  ) temp

WHERE temp.empno=7369 ;

 

分析40：本程序由于需要针对于每一个部门找出整个部门的工资统计信息，所以可以利用分窗子句完成，而每一个分窗子句的范围应该是所有数据，所以可以使用“RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING”作为范围限定。

SELECT e.empno , e.ename , e.sal , d.dname , d.loc ,

    ROUND(AVG(sal) OVER (PARTITION BY e.deptno ORDER BY sal

          RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)) avg_salary ,

    MAX(sal) OVER (PARTITION BY e.deptno ORDER BY sal

          RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) max_salary ,

    MIN(sal) OVER (PARTITION BY e.deptno ORDER BY sal

          RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) min_salary

FROM emp e,dept d

WHERE e.deptno=d.deptno ;

 

范例41：观察RANK()和DENSE_RANK()函数

SELECT deptno,ename,sal,

    RANK() OVER (PARTITION BY deptno ORDER BY sal) rank_result ,

    DENSE_RANK() OVER (PARTITION BY deptno ORDER BY sal) dense_rank_result

FROM emp ;

 

范例42：使用ROW_NUMBER()函数

SELECT deptno,ename,sal,

    ROW_NUMBER() OVER (PARTITION BY deptno ORDER BY sal) row_result_deptno ,

    ROW_NUMBER() OVER (ORDER BY sal) row_result_all

FROM emp ;

 

范例43：查询每个部门的最高及最低工资

SELECT deptno,

    MAX(sal) KEEP (DENSE_RANK FIRST ORDER BY sal DESC) max_salary ,

    MIN(sal) KEEP (DENSE_RANK LAST ORDER BY sal DESC) min_salary

FROM emp

GROUP BY deptno ;

 

范例44：验证FIRST_VALUE()与LAST_VALUE()函数

SELECT deptno , empno , ename , sal ,

      FIRST_VALUE(sal) OVER (PARTITION BY deptno ORDER BY sal

            RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) first_result ,

      LAST_VALUE(sal) OVER (PARTITION BY deptno ORDER BY sal

            RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) last_result

FROM emp

WHERE deptno=10 ;

 

范例45：观察LAG()与LEAD()函数

SELECT deptno , empno , ename , sal ,

      LAG(sal,2,0) OVER (PARTITION BY deptno ORDER BY sal ) lag_result ,

      LEAD(sal,2,0) OVER (PARTITION BY deptno ORDER BY sal ) lead_result

FROM emp

WHERE deptno=20 ;

 

范例46：验证CUME_DIST()函数

SELECT deptno,ename,sal ,

      CUME_DIST() OVER (PARTITION BY deptno ORDER BY sal) cume

FROM emp

WHERE deptno IN (10,20) ;

 

范例47：使用NTILE()函数

SELECT deptno , sal ,

      SUM(sal) OVER (PARTITION BY deptno ORDER BY sal) sum_result ,

      NTILE(3) OVER (PARTITION BY deptno ORDER BY sal) ntile_result_a ,

      NTILE(6) OVER (PARTITION BY deptno ORDER BY sal) ntile_result_b

FROM emp ;

 

范例48：计算各部门工资所占的总工资比率

SELECT deptno ,SUM(sal) ,

      ROUND(RATIO_TO_REPORT(SUM(sal)) OVER () ,5)  rate ,

      ROUND(RATIO_TO_REPORT(SUM(sal)) OVER () ,5) * 100 || '%' precent

FROM emp

GROUP BY deptno;

范例49：查询每个部门中各个职位的总工资

SELECT deptno , job , SUM(sal)

FROM emp

GROUP BY deptno , job ;

SELECT deptno ,

SUM(DECODE(job, 'PRESIDENT' , sal , 0 )) PRESIDENT_JOB ,

SUM(DECODE(job, 'MANAGER' , sal , 0)) MANAGER_JOB ,

SUM(DECODE(job , 'ANALYST' , sal , 0 )) ANALYST_JOB ,

SUM(DECODE(job , 'CLERK' , sal, 0 )) CLERK_JOB ,

SUM(DECODE(job , 'SALESMAN' , sal , 0)) SALESMAN_JOB

FROM emp

GROUP BY deptno ;

 

范例50：不使用DECODE()函数实现

SELECT temp.dno, SUM(president_job) , SUM(manager_job) , SUM(analyst_job) , SUM(clerk_job) , SUM(salesman_job)

FROM (

      SELECT deptno dno ,

            (SELECT SUM(sal) FROM emp WHERE job='PRESIDENT' AND empno=e.empno) PRESIDENT_JOB ,

            (SELECT SUM(sal) FROM emp WHERE job='MANAGER' AND empno=e.empno) MANAGER_JOB ,

            (SELECT SUM(sal) FROM emp WHERE job='ANALYST' AND empno=e.empno) ANALYST_JOB ,

            (SELECT SUM(sal) FROM emp WHERE job='CLERK' AND empno=e.empno) CLERK_JOB ,

            (SELECT SUM(sal) FROM emp WHERE job='SALESMAN' AND empno=e.empno) SALESMAN_JOB

FROM emp e ) temp

GROUP BY temp.dno

ORDER BY temp.dno DESC ;

 

范例51：利用PIVOT函数实现转换

SELECT * FROM (SELECT deptno , job , sal FROM emp)

PIVOT (

SUM(sal)

FOR job IN (

'PRESIDENT' AS president_job ,

'MANAGER' AS manager_job ,

'ANALYST' AS analyst_job ,

'CLERK' AS clerk_job ,

'SALESMAN' AS salesman_job

)

) ORDER BY deptno ;

 

范例52：输出为XML

SELECT * FROM (SELECT deptno , job , sal FROM emp)

PIVOT XML (

        SUM(sal)

        FOR job IN (ANY)

) ORDER BY deptno ;

 

范例53：查询更多统计信息

SELECT * FROM (

      SELECT job ,deptno , sal,

      SUM(sal) OVER(PARTITION BY deptno) sum_sal  ,

      MAX(sal) OVER(PARTITION BY deptno) max_sal ,

      MIN(sal) OVER(PARTITION BY deptno) min_sal

      FROM emp)

PIVOT (

SUM(sal)

FOR job IN (

'PRESIDENT' AS president_job ,

'MANAGER' AS manager_job ,

'ANALYST' AS analyst_job ,

'CLERK' AS clerk_job ,

'SALESMAN' AS salesman_job

)

) ORDER BY deptno ;

范例54：设置多个统计函数。查询出每个部门不同职位的总工资，和每个部门不同职位的最高工资

SELECT * FROM (SELECT deptno , job , sal FROM emp)

PIVOT (

SUM(sal) AS sum_sal , MAX(sal) AS sum_max

FOR job IN (

'PRESIDENT' AS president_job ,

'MANAGER' AS manager_job ,

'ANALYST' AS analyst_job ,

'CLERK' AS clerk_job ,

'SALESMAN' AS salesman_job

)

) ORDER BY deptno ;

 

范例55：修改表结构及更新数据

ALTER TABLE emp ADD (sex VARCHAR2(10) DEFAULT '男') ;

UPDATE emp SET sex='女' WHERE TO_CHAR(hiredate,'yyyy')='1981' ;

COMMIT ;

 

范例56：设置多个统计列

SELECT * FROM (SELECT deptno , job , sal , sex FROM emp)

PIVOT (

SUM(sal) AS sum_sal , MAX(sal) AS sum_max

FOR (job, sex) IN (

   ('MANAGER','男') AS manager_male_JOB ,

   ('MANAGER','女') AS manager_female_JOB ,

   ('CLERK','男') AS clerk_male_JOB ,

   ('CLERK','女') AS clerk_female_JOB

)

) ORDER BY deptno ;

 

范例57：验证UNPIVOT函数

WITH temp AS (

    SELECT * FROM (SELECT deptno , job , sal FROM emp)

    PIVOT (

            SUM(sal)

            FOR job IN (

                    'PRESIDENT' AS PRESIDENT_JOB ,

                    'MANAGER' AS MANAGER_JOB ,

                    'ANALYST' AS ANALYST_JOB ,

                    'CLERK' AS CLERK_JOB ,

                    'SALESMAN' AS SALESMAN_JOB

            )

    ) ORDER BY deptno )

SELECT * FROM temp

UNPIVOT (

    sal_sum FOR job IN (

      president_job AS 'PRESIDENT' ,

      manager_job AS 'MANAGER' ,

      analyst_job AS 'ANALYST' ,

      clerk_job AS 'CLERK' ,

      salesman_job AS 'SALESMAN'

    )

) ORDER BY deptno ;

 

范例58：显示所有数据

WITH temp AS (

    SELECT * FROM (SELECT deptno , job , sal FROM emp)

    PIVOT (

            SUM(sal)

            FOR job IN (

                    'PRESIDENT' AS PRESIDENT_JOB ,

                    'MANAGER' AS MANAGER_JOB ,

                    'ANALYST' AS ANALYST_JOB ,

                    'CLERK' AS CLERK_JOB ,

                    'SALESMAN' AS SALESMAN_JOB

            )

    ) ORDER BY deptno )

SELECT * FROM temp

UNPIVOT INCLUDE NULLS(

    sal_sum FOR job IN (

      president_job AS 'PRESIDENT' ,

      manager_job AS 'MANAGER' ,

      analyst_job AS 'ANALYST' ,

      clerk_job AS 'CLERK' ,

      salesman_job AS 'SALESMAN'

    )

) ORDER BY deptno ;

 

范例59：观察分层的基本关系

SELECT empno,LPAD('|- ' , LEVEL * 2 , ' ') || ename empname ,mgr,LEVEL

FROM emp

CONNECT BY PRIOR empno=mgr

START WITH mgr IS NULL ;

 

范例60：利用“CONNECT_BY_ISLEAF”判断某一个节点是根节点还是叶子节点

SELECT empno,LPAD('|- ' , LEVEL * 2 , ' ') || ename empname ,mgr,LEVEL ,

      DECODE (CONNECT_BY_ISLEAF , 0 , '根节点' , 1 , '   叶子节点') isleaf

FROM emp

CONNECT BY PRIOR empno=mgr

START WITH mgr IS NULL ;

 

范例61：使用“CONNECT_BY_ROOT”语句

SELECT empno,LPAD('|- ' , LEVEL * 2 , ' ') || ename empname ,mgr,LEVEL ,

     CONNECT_BY_ROOT ename

FROM emp

CONNECT BY PRIOR empno=mgr

START WITH empno=7566 ;   è  此处直接从7566数据开始列出

 

范例62：使用SYS_CONNECT_BY_PATH()函数取得节点路径信息

SELECT empno,LPAD('|- ' , LEVEL * 2 , ' ') || SYS_CONNECT_BY_PATH(ename,' => ') empname ,mgr,LEVEL ,

      DECODE (CONNECT_BY_ISLEAF , 0 , '根节点' , 1 , '   叶子节点') isleaf

FROM emp

CONNECT BY PRIOR empno=mgr

START WITH mgr IS NULL ;

 

范例63：去掉某一节点

SELECT empno,LPAD('|- ' , LEVEL * 2 , ' ') || SYS_CONNECT_BY_PATH(ename,' => ') empname ,mgr,LEVEL ,

      DECODE (CONNECT_BY_ISLEAF , 0 , '根节点' , 1 , '   叶子节点') isleaf

FROM emp

CONNECT BY PRIOR empno=mgr AND empno!=7698

START WITH mgr IS NULL ;

范例64：破坏程序结构的显示

SELECT ename,LPAD('|- ' , LEVEL * 2 , ' ') || ename empname ,LEVEL ,

      DECODE (CONNECT_BY_ISLEAF , 0 , '根节点' , 1 , '   叶子节点') isleaf

FROM emp

CONNECT BY PRIOR empno=mgr

START WITH mgr IS NULL

ORDER BY ename ;

 

范例65：利用“ORDER SIBLINGS”保持层次关系

SELECT ename,LPAD('|- ' , LEVEL * 2 , ' ') || ename empname ,LEVEL ,

      DECODE (CONNECT_BY_ISLEAF , 0 , '根节点' , 1 , '   叶子节点') isleaf

FROM emp

CONNECT BY PRIOR empno=mgr

START WITH mgr IS NULL

ORDER siblings BY ename ;

 

范例66：将KING的领导编号变为7698

UPDATE emp SET mgr=7698 WHERE empno=7839 ;

 

范例67：判断循环

SELECT ename,LPAD('|- ' , LEVEL * 2 , ' ') || ename empname ,LEVEL ,

      DECODE (CONNECT_BY_ISLEAF , 0 , '根节点' , 1 , '   叶子节点') isleaf ,

      DECODE(CONNECT_BY_ISCYCLE , 0 , '【√】没有循环' , 1 , '〖×〗存在循环') iscycle

FROM emp

CONNECT BY NOCYCLE PRIOR empno=mgr

START WITH empno=7839

ORDER siblings BY ename ;