DB2 SQL for the 21 st Century: Overlooked Enhancements. David Simpson

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1 DB2 SQL for the 21 st Century: Overlooked Enhancements David Simpson

2 Themis Education Most complete DB2 Curriculum in the industry Offerings include a complete mainframe curriculum in addition to Oracle, Java,.NET, Linux, UNIX, etc. Training Venues: At your facility for groups Public enrollment at various locations in the USA Distance learning public enrollment with live instructors. Webinars: Visit for upcoming schedule and replays of past webinars and to download today s slides.

3 David Simpson David Simpson is currently the Vice President of Themis Inc. He teaches courses on SQL, Application Programming, Database Administration as well as optimization, performance and tuning. He also installs and maintains the database systems used for training at Themis and works with our network of instructors to deliver high quality training solutions to our customers worldwide. Since 1993 David has worked as a developer and DBA in support of very large transactional and business intelligence systems. David is a certified DB2 DBA on both z/os and LUW. David was voted Best User Speaker and Best Overall Speaker at IDUG North America He was also voted Best User Speaker at IDUG Europe 2006 and is a member of the IDUG Speakers Hall of Fame. David is also an IBM Champion for Information Management. dsimpson@themisinc.com

4 This material comes from Themis course: DB1041: Advanced SQL for DB2 Description March 14 Offering

5 Built-in Functions for Ranking and Numbering (DB2 9)

6 Rank Function SELECT LASTNAME, SALARY, RANK() OVER(ORDER BY SALARY DESC) AS R FROM EMP ORDER BY SALARY DESC LASTNAME SALARY R HAAS MOON LUCCHESI THOMPSON GEYER KWAN PULASKI

7 Rank Function SELECT LASTNAME, SALARY, RANK() OVER(ORDER BY SALARY DESC) AS R FROM EMP ORDER BY LASTNAME LASTNAME SALARY R ADAMSON BROWN GEYER GOUNOT HAAS HENDERSON JEFFERSON

8 Rank Function with Partitioning SELECT DEPTNO, LASTNAME, SALARY, RANK() OVER(PARTITION BY DEPTNO ORDER BY SALARY DESC) AS R FROM EMP ORDER BY DEPTNO, SALARY DESC DEPTNO LASTNAME SALARY R A00 HAAS A00 MOON A00 LUCCHESI A00 O CONNEL B01 THOMPSON C01 KWAN C01 NICHOLS C01 QUINTANA

9 Dense Rank Function SELECT LASTNAME, SALARY, DENSE_RANK() OVER(ORDER BY SALARY DESC) AS R FROM EMP ORDER BY SALARY DESC LASTNAME SALARY R HAAS MOON LUCCHESI THOMPSON GEYER KWAN PULASKI

10 Row Numbering SELECT LASTNAME, SALARY, ROW_NUMBER() OVER(ORDER BY SALARY DESC) AS R FROM EMP ORDER BY SALARY DESC LASTNAME SALARY R HAAS MOON LUCCHESI THOMPSON GEYER KWAN PULASKI

11 More Complex ORDER BY SELECT LASTNAME, SALARY, ROW_NUMBER() OVER(ORDER BY SALARY DESC, BONUS DESC) AS R FROM EMP ORDER BY SALARY DESC LASTNAME SALARY BONUS R HAAS MOON LUCCHESI THOMPSON GEYER KWAN PULASKI

12 Moving Aggregates (DB2 10)

13 Moving Aggregates Allows for a running total, average, etc Works with aggregate or column functions AVG SUM MIN MAX ORDER BY in the OVER should match the final for the statement 1-13

14 Moving Sum / Avg Example 1: SELECT EMPNO, DEPTNO, SALARY, SUM (SALARY) OVER (ORDER BY SALARY ASC ROWS UNBOUNDED PRECEDING ) AS SUM_SAL FROM EMP ORDER BY SALARY ASC

15 Result EMPNO DEPTNO SALARY SUM_SAL E E D E D D E D D D

16 Moving Sum / Avg Example 1: SELECT EMPNO, DEPTNO, SALARY, SUM (SALARY) OVER (ORDER BY SALARY ASC ROWS UNBOUNDED PRECEDING ) AS SUM_SAL FROM EMP ORDER BY SALARY ASC

17 Result EMPNO DEPTNO SALARY SUM_SAL E E D E D D E D D D

18 Moving Sum / Avg Example 2: SELECT DEPTNO, EMPNO, SALARY, SUM (SALARY) OVER (PARTITION BY DEPTNO ORDER BY SALARY ASC ROWS UNBOUNDED PRECEDING ) AS SUM_SAL FROM EMP ORDER BY DEPTNO, SALARY

19 Result DEPTNO EMPNO SALARY SUM_SAL A A A A B C C C SUM resets for each new value of partition clause

20 Moving Sum / Avg Example 3: Rows n Preceding SELECT DEPTNO, EMPNO, SALARY, AVG(SALARY) OVER (PARTITION BY DEPTNO ORDER BY SALARY ASC ROWS 2 PRECEDING ) AS AVG_SAL FROM EMP ORDER BY DEPTNO, SALARY SELECT DEPTNO, EMPNO, SALARY, DEC(ROUND(AVG(SALARY) OVER (PARTITION BY DEPTNO ORDER BY SALARY ASC ROWS 2 PRECEDING ),2),9,2) AS AVG_SAL FROM EMP ORDER BY DEPTNO, SALARY CAST final number as a shortened, rounded number

21 A Word on Rounding SELECT CAST( AS DECIMAL(9,2)) SELECT ROUND( , 2) SELECT ROUND(CAST( AS DECIMAL(9,2)),2) SELECT CAST(ROUND( , 2) AS DECIMAL(9,2)) 3.78

22 V10 OLAP Moving Ranges ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING ROWS BETWEEN 2 PRECEDING AND CURRENT ROW ROWS BETWEEN 2 PRECEDING AND 1 PRECEDING

23 Other Windowing Options RANGE BETWEEN PRECEDING AND FOLLOWING RANGE BETWEEN PRECEDING AND CURRENT ROW

24 Windowing by RANGE SELECT DEPTNO, EMPNO, SALARY, SUM (SALARY) OVER (ORDER BY SALARY ASC RANGE BETWEEN 5000 PRECEEDING AND CURRENT ROW ) AS SUM_SAL FROM EMP ORDER BY DEPTNO

25 Result DEPTNO EMPNO SALARY SUM_SAL E E D E D D E D D D Only values within $5000 are summed with the current row

26 Advanced Grouping (V11)

27 GROUPING SETS With 2 Groups SELECT DEPTNO, JOB, AVG(SALARY) AS AVG FROM EMP WHERE DEPTNO < 'B99' GROUP BY GROUPING SETS ( (DEPTNO, JOB), (DEPTNO) ) ORDER BY DEPTNO, JOB DEPTNO JOB AVG A00 CLERK A00 PRES A00 SALESREP A B01 MANAGER B

28 GROUPING SETS With 3 Groups SELECT DEPTNO, JOB, AVG(SALARY) AS AVG FROM EMP WHERE DEPTNO < 'B99' GROUP BY GROUPING SETS ( (DEPTNO, JOB), (DEPTNO), ( ) ) ORDER BY DEPTNO, JOB DEPTNO JOB AVG A00 CLERK A00 PRES A00 SALESREP A B01 MANAGER B

29 ROLLUP SELECT DEPTNO, JOB, AVG(SALARY) AS AVG FROM EMP WHERE DEPTNO < 'B99' GROUP BY ROLLUP (DEPTNO, JOB) ORDER BY DEPTNO, JOB DEPTNO JOB AVG A00 CLERK A00 PRES A00 SALESREP A B01 MANAGER B

30 ROLLUP With 2 Columns GROUP BY ROLLUP (DEPTNO, JOB) GROUP BY GROUPING SETS ( (DEPTNO, JOB), (DEPTNO), ( ) ) =

31 ROLLUP With 3 Columns GROUP BY ROLLUP (DEPTNO, JOB, EDLEVEL) = GROUP BY GROUPING SETS ( (DEPTNO, JOB, EDLEVEL), (DEPTNO, JOB), (DEPTNO) ( ) )

CUBE SELECT DEPTNO, JOB, AVG(SALARY) AS AVG FROM EMP WHERE DEPTNO < 'B99' GROUP BY CUBE (DEPTNO, JOB) ORDER BY DEPTNO, JOB DEPTNO JOB AVG A00 CLERK 29250.

32 CUBE SELECT DEPTNO, JOB, AVG(SALARY) AS AVG FROM EMP WHERE DEPTNO < 'B99' GROUP BY CUBE (DEPTNO, JOB) ORDER BY DEPTNO, JOB DEPTNO JOB AVG A00 CLERK A00 PRES A00 SALESREP A B01 MANAGER B CLERK PRES SALESREP MANAGER

33 CUBE With 2 Columns GROUP BY CUBE (DEPTNO, JOB) GROUP BY GROUPING SETS ( (DEPTNO, JOB), (DEPTNO), (JOB), ( ) ) =

34 CUBE With 3 Columns GROUP BY CUBE (DEPTNO, JOB, EDLEVEL) = GROUP BY GROUPING SETS ( (DEPTNO, JOB, EDLEVEL), (DEPTNO, JOB), (DEPTNO, EDLEVEL), (JOB, EDLEVEL), (DEPTNO), (JOB), (EDLEVEL), ( ) )

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