SQL techniques for faster applications

WE
ARE
SHOWING
CODING SAMPLES
SO IF YOU HAVE PASSED
THE AGE OF TWENTY THEN YOU SHOULD PROBABLY THINK
ABOUT SITTING RIGHT UP CLOSE TO THE FRONT OF THE ROOM BECAUSE OTHERWISE YOU MIGHT MISS OUT
A N D I F Y O U C A N R E A D T H I S, T H E N Y O U S H O U L D L E A V E B E C A U S E Y O U H A V E S U P E R P O W E R S A N D Y O U S H O U L D B E I N A N A V E N G E R S M O V I E N O T L E A R N I N G A B O U T I N F O R M A T I O N T E C H N O L O G Y. :-)

6
@connor_mc_d connormcdonald.wordpress.com

7
https://www.youtube.com/c/ConnorMcDonaldOracle
https://www.facebook.com/connor.mcdonald42

coding for functionality ...
17

... not for data processing
18

... can make your apps awesome
20

SQL> with x( s, ind ) as
2 ( select sud, instr( sud, '.' )
3 from ( select replace(replace(
4 replace(replace(:board,'-'),'|'),' '),chr(10)) sud
5 from dual )
6 union all
7 select substr(s,1,ind-1)||z||substr(s,ind+1)
8 , instr(s,'.',ind+1)
9 from x
10 , ( select to_char( rownum ) z
11 from dual connect by rownum <= 9 ) z
12 where ind > 0
13 and not exists (
14 select null
15 from ( select rownum lp from dual
16 connect by rownum <= 9 )
17 where z = substr(s,trunc((ind-1)/9)*9+lp,1)
25

18 or z = substr(s,mod(ind-1,9)-8+lp*9,1)
19 or z = substr(s,mod(trunc((ind-1)/3),3)*3
20 +trunc((ind-1)/27)*27+lp
21 +trunc((lp-1)/3)*6,1)
22 )
23 ),
24 result as (
25 select s
26 from x
27 where ind = 0 )
28 select
29 regexp_replace(substr(s,(idx-1)*9+1,9),
30 '(...)(...)(...)',
31 '1|2|3')||
32 case when mod(idx,3)=0 then chr(10)||rpad('-',11,'-') end soln
33 from result,
34 ( select level idx
35 from dual
36 connect by level <= 9 )
26
Ack: Anton Scheffer,
https://technology.amis.nl

SQL> variable board varchar2(1000)
SQL> begin :board :=
2 '53.|.7.|...
3 6..|195|...
4 .98|...|.6.
5 -----------
6 8..|.61|..3
7 4..|8.3|..1
8 7..|.2.|..6
9 -----------
10 .6.|...|28.
11 ...|419|..5
12 ...|.8.|.79
13 ';
14 end;
27
5 3 7
6 1 9 5
9 8 6
8 6 1 3
4 8 3 1
7 2 6
6 2 8
4 1 9 5
8 7 9

SOLUTION
-----------
534|678|912
672|195|348
198|342|567
-----------
859|761|423
426|853|791
713|924|856
-----------
961|537|284
287|419|635
345|286|179
-----------
28
sud.sql

29
100%
% of developers that
will need to solve Sudoku
as part of their job

30
100%
% of developers that need
to get real stuff done

SQL techniques for faster applications

"What if I don't have a TAB200K ?"
41
insert into my_transactions1
select ...
from tab200k;

databases store data
43
only just enough

44
SQL> select * from meetings;
SCHEDULED OWNER
--------- -------------------------
06-MAY-17 Connor
13-MAY-17 Gerald
17-MAY-17 Maria

45
Connor
Gerald
Maria
free free free free free free
free free free free free free
free free free free free
free free free
free free freefree free free
freefree

47
SQL> select * from meetings;
SCHEDULED OWNER
--------- -----------------------
01-MAY-17
02-MAY-17
03-MAY-17
04-MAY-17
05-MAY-17
06-MAY-17 Connor
07-MAY-17
08-MAY-17
...
16-MAY-17
17-MAY-17 Maria
18-MAY-17
19-MAY-17
...
30-MAY-17
31-MAY-17

SQL> select level seq
2 from DUAL
3 connect by level <= 10;
SEQ
----------
1
2
3
4
5
6
7
8
9
10
10 rows selected.
51
Oracle

select *
from generate_series(1, 10)
52
with gen(seq) as (
select 1 seq
union all
select seq+1 from gen
where seq < 10
)
select * from gen;
select seq
from my_n_row_table
Postgres
SQL Server
MySQL

SQL> select level seq
2 from DUAL
-----------------------------------------------------
| Id | Operation | Name | Rows |
-----------------------------------------------------
| 0 | SELECT STATEMENT | | 1 |
|* 1 | CONNECT BY WITHOUT FILTERING| | |
| 2 | FAST DUAL | | 1 |
-----------------------------------------------------
Statistics
------------------------------
1 recursive calls
0 db block gets
0 consistent gets
0 physical reads
53

SQL> select date '2017-04-30'+level dte
2 from dual
DTE
---------
01-MAY-17
02-MAY-17
03-MAY-17
04-MAY-17
...
...
29-MAY-17
30-MAY-17
31-MAY-17
31 rows selected.
57

59
SQL> select
2 dte scheduled,
3 m.owner
4 from
5 ( select date '2017-04-30'+level dte
6 from dual
7 connect by level <= 31 ) d
8 left outer join
9 meetings m
10 on d.dte = m.scheduled
11 order by 1;
SCHEDULED OWNER
--------- -----------------------
01-MAY-17
02-MAY-17
03-MAY-17
04-MAY-17
05-MAY-17
06-MAY-17 Connor
07-MAY-17
08-MAY-17
...
16-MAY-17
17-MAY-17 Maria
18-MAY-17
19-MAY-17
...
30-MAY-17
31-MAY-17

SQL> WITH last_hire AS
2 ( select deptno, max(hiredate)
3 from emp
4 group by deptno
5 )
6 select * from last_hire;
DEPTNO MAX(HIRED
---------- ---------
30 03-DEC-81
20 12-JAN-83
10 23-JAN-82
64

"gee....... more code, same result"
65

WITH last_hire AS
(
select deptno, max(hiredate)
from emp
group by deptno
)
select * from last_hire;
66

relational is a rigorous model ...
69

relational ... can sortta suck :-)
71

"data is represented as mathematical n-ary
relations, an n-ary relation being a subset of the
Cartesian product of n domains."
74

"First, get the total salary paid by each department,
then get the average of these totals,
then list those departments above that average"
77
SQL ?

"First, get the total salary paid by department...
SQL> WITH dept_salaries AS (
2 SELECT dname, SUM(sal) dept_sal
3 FROM emp e, dept d
4 WHERE e.deptno = d.deptno
5 GROUP BY dname),
78

"...then get the average of these totals...
6 avg_sal AS ( SELECT AVG(dept_sal) avsal
7 FROM dept_salaries)
79

"...then list those departments above average."
8 SELECT * FROM dept_salaries d, avg_sal a
9 WHERE d.dept_sal > a.avsal
10 ORDER BY d.dname;
80

5 GROUP BY dname),
81

recall : 31 days of meetings
85

86
SQL> with raw_data as (
2 select
3 dte scheduled,
4 m.owner
5 from
6 ( select date '2017-04-30'+level dte
7 from dual
8 connect by level <= 31 ) d
9 left outer join
10 meetings m
11 on d.dte = m.scheduled
12 )
13 select
14 json_arrayagg(
15 json_object(key to_char(scheduled) value owner )
16 order by scheduled ) as meetings
17 from raw_data ;
[{"01-MAY-17":null},
{"02-MAY-17":null},
{"03-MAY-17":null},
{"04-MAY-17":null},
{"05-MAY-17":null},
{"06-MAY-17":"Connor"},
{"07-MAY-17":null},
{"08-MAY-17":null},
{"09-MAY-17":null},
{"10-MAY-17":null},
...
...
...
{"30-MAY-17":null},
{"31-MAY-17":null}
]

90
5 GROUP BY dname),
join

----------------------------------------------------------------------
| Id | Operation | Name |
----------------------------------------------------------------------
| 0 | SELECT STATEMENT | |
| 1 | TEMP TABLE TRANSFORMATION | |
| 2 | LOAD AS SELECT | |
| 3 | HASH GROUP BY | |
| 4 | MERGE JOIN | |
| 5 | TABLE ACCESS BY INDEX ROWID| DEPT |
| 6 | INDEX FULL SCAN | PK_DEPT |
| 7 | SORT JOIN | |
| 8 | TABLE ACCESS FULL | EMP |
| 9 | SORT ORDER BY | |
| 10 | NESTED LOOPS | |
| 11 | VIEW | |
| 12 | SORT AGGREGATE | |
| 13 | VIEW | |
| 14 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6624_AF422F5 |
| 15 | VIEW | |
| 16 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6624_AF422F5 |
----------------------------------------------------------------------
91

SQL> alter session set sql_trace = true;
Session altered.
5 GROUP BY dname),
6 avg_sal AS ( SELECT AVG(dept_sal) asal
9 WHERE d.dept_sal > a.asal
DNAME DEPT_SAL ASAL
-------------- ---------- ----------
RESEARCH 21750 19350
SQL> alter session set sql_trace = false;
Session altered.
92

PARSING IN CURSOR #12 len=179 dep=1 uid=0 oct=1...
CREATE GLOBAL TEMPORARY
TABLE "SYS"."SYS_TEMP_0FD9D6625_AF422F5"
("C0" VARCHAR2(14),"C1" NUMBER )
IN_MEMORY_METADATA CURSOR_SPECIFIC_SEGMENT
STORAGE (OBJNO 4254950949 ) NOPARALLEL
END OF STMT
93

------------------------------------------------------
| Id | Operation | Name |
------------------------------------------------------
| 0 | SELECT STATEMENT | |
| 1 | SORT ORDER BY | |
| 2 | NESTED LOOPS | |
| 3 | VIEW | |
| 4 | SORT AGGREGATE | |
| 5 | VIEW | |
| 6 | HASH GROUP BY | |
| 8 | TABLE ACCESS BY INDEX ROWID| DEPT |
| 10 | SORT JOIN | |
| 12 | VIEW | |
| 13 | SORT GROUP BY | |
| 15 | TABLE ACCESS BY INDEX ROWID | DEPT |
| 17 | SORT JOIN | |
------------------------------------------------------
95

98
SQL> select *
2 from timeslots;
HR
--
8
9
10
11
12
13
14
15
16
SQL> select *
2 from bookings;
HR ROOM WHO
------- ---------- -------
8 Room2 PETE
9 Room1 JOHN
11 Room1 MIKE
14 Room2 JILL
15 Room2 JANE
16 Room1 SAM

bookings by hour
99
conventional outer join

100
SQL> SELECT hrs.hr, t1.room, t1.who
2 from timeslots hrs
3 left outer join bookings t1
4 on hrs.hr = t1.hr
HR ROOM WHO
------- ---------- ----------
8 Room2 PETE
9 Room1 JOHN
10
11 Room1 MIKE
12
13
14 Room2 JILL
15 Room2 JANE
16 Room1 SAM
100

102
HR ROOM WHO
------- ---------- ----------
8 Room2 PETE
9
10
11
12
13
14 Room2 JILL
15 Room2 JANE
16
HR ROOM WHO
------- ---------- ----------
8
9 Room1 JOHN
10
11 Room1 MIKE
12
13
14
15
16 Room1 SAM

103
SQL> select *
2 from timeslots;
HR
--
8
9
10
11
12
13
14
15
16
x "Room 1"
x "Room 2"
...
x "Room n"

105
SQL> SELECT hrs.hr, t1.room, t1.who
2 FROM bookings t1
3 PARTITION BY (t1.room)
4 RIGHT OUTER JOIN hrs ON (hrs.hr = t1.hr);
HR ROOM WHO
--------- ---------- ----------
8 Room1
9 Room1 JOHN
10 Room1
11 Room1 MIKE
12 Room1
13 Room1
14 Room1
15 Room1
16 Room1 SAM
8 Room2 PETE
9 Room2
10 Room2
11 Room2
12 Room2
13 Room2
14 Room2 JILL
15 Room2 JANE
16 Room2
105

108
"employees by hiredate, recent first"

SQL> select empno, ename, hiredate
2 from emp
3 limit 5
4 order by hiredate desc;
EMPNO ENAME HIREDATE
---------- ---------- -------------------
7654 MARTIN 28/09/1981 00:00:00
7566 JONES 02/04/1981 00:00:00
7521 WARD 22/02/1981 00:00:00
7499 ALLEN 20/02/1981 00:00:00
7369 SMITH 17/12/1980 00:00:00
109

2 from emp
3 where rownum <= 5
4 order by hiredate desc;
---------- ---------- -------------------
7654 MARTIN 28/09/1981 00:00:00
7566 JONES 02/04/1981 00:00:00
7521 WARD 22/02/1981 00:00:00
7499 ALLEN 20/02/1981 00:00:00
7369 SMITH 17/12/1980 00:00:00
110

SQL> select *
2 from (
3 select empno, ename, hiredate
4 from emp
5 order by hiredate desc
6 )
7 where rownum <= 5;
---------- ---------- ---------
7876 ADAMS 12-JAN-83
7788 SCOTT 09-DEC-82
7934 MILLER 23-JAN-82
7900 JAMES 03-DEC-81
7902 FORD 03-DEC-81
112

SQL> select *
2 from (
3 select
4 empno, ename, hiredate,
5 row_number() over ( order by hiredate desc) rn
6 from emp
7 )
8 where rn <= 5;
113

2 from emp
4 fetch first 5 rows only;
---------- ---------- ---------
7876 ADAMS 12-JAN-83
7788 SCOTT 09-DEC-82
7934 MILLER 23-JAN-82
7900 JAMES 03-DEC-81
7902 FORD 03-DEC-81
114

115
"TL;DR ... my app can do it"

public static void Paging(Connection conn ) throws Exception
{
PreparedStatement sql_stmt =
conn.prepareStatement(
"select empno, ename, hiredate
from emp
order by hiredate desc");
ResultSet rset = sql_stmt.executeQuery();
int i = 0;
while( rset.next() )
{
...
i = i + 1;
if (i > 5) {
break;
}
}
rset.close();
}
116

SQL> select *
2 from (
3 select empno, ename, hiredate
4 from emp
6 )
7 where rownum <= 5;
121
------------------------------------------------
------------------------------------------------
|* 1 | COUNT STOPKEY | | |
| 2 | VIEW | | 14 |
|* 3 | SORT ORDER BY STOPKEY| | 14 |
| 4 | TABLE ACCESS FULL | EMP | 14 |
------------------------------------------------

2 from emp
4 fetch first 5 rows only;
122
-------------------------------------------------
-------------------------------------------------
|* 1 | VIEW | | 14 |
|* 2 | WINDOW SORT PUSHED RANK| | 14 |
| 3 | TABLE ACCESS FULL | EMP | 14 |
-------------------------------------------------

you get other benefits
123
oc02.sql

124
"but what about the next page ?"

2 from emp
4 offset 5 rows fetch first 5 rows only;
---------- ---------- ---------
7839 KING 17-NOV-81
7654 MARTIN 28-SEP-81
7844 TURNER 08-SEP-81
7782 CLARK 09-JUN-81
7698 BLAKE 01-MAY-81
127

128
"an expensive query per page ?!?!

SQL> with first_200 as
2 ( select f.*, rownum r
3 from
4 ( select *
5 from t
6 order by owner, object_name desc
7 ) f
8 where rownum <= 200
9 )
10 select *
11 from first_200
12 where r <= 10
130
/*+ result_cache */ rownum r, f.*
oc03.sql
r between 11 and 20

C#, C++ ESB Tuxedo
Weblogic
Stored
Procedure
133

for (int i = 0; i < WinningCombinations.Count; ++i)
{
if (WinningCombinations[i].Investment > 0 &&
WinningCombinations[i].PrimaryDividend > MinDividendDeadHeat)
{
maxDivisor =
Math.Max(maxDivisor, WinningCombinations[i].Divisor);
}
}
for (int i = 0; i < WinningCombinations.Count; ++i)
{
if (WinningCombinations[i].Investment > 0 &&
WinningCombinations[i].PrimaryDividend > MinDividendDeadHeat)
{
WinningCombinations[i].Divisor =
maxDivisor / WinningCombinations[i].Divisor;
sumNewDivisors += WinningCombinations[i].Divisor;134

SQL should "self document"
140

query blocks =
self-documenting SQL
141

select emp.*
from emp,
( select trunc(hiredate,'YYYY'), max(empno) empno
from emp
where empno > 0
group by trunc(hiredate,'YYYY') ) x,
( select deptno, avg(sal)
from emp
group by deptno ) y
where x.empno = emp.empno
and y.deptno = emp.deptno
142

Id | Operation | Name |
----------------------------------------------|
0 | SELECT STATEMENT | |
1 | HASH JOIN | |
2 | TABLE ACCESS BY INDEX ROWID | EMP |
3 | NESTED LOOPS | |
4 | VIEW | |
5 | SORT GROUP BY | |
6 | TABLE ACCESS BY INDEX ROWID| EMP |
7 | INDEX FULL SCAN | E2 |
8 | INDEX RANGE SCAN | E1 |
9 | VIEW | |
143

?
144
select emp.*
from emp,
( select trunc(hiredate,'YYYY'), max(empno) empno
from emp
where empno > 0
( select deptno, avg(sal)
from emp
group by deptno ) y
Id | Operation | Name |
----------------------------------------------|
1 | HASH JOIN | |
4 | VIEW | |
9 | VIEW | |

select emp.*
from emp,
( select /*+ QB_NAME(YR_HIRE) */
trunc(hiredate,'YYYY'), max(empno) empno
from emp
where empno > 0
( select /*+ QB_NAME(AV_SAL) */
deptno, avg(sal)
from emp
group by deptno ) y
145
select emp.*
from emp,
( select /*+ QB_NAME(YR_HIRE) */
trunc(hiredate,'YYYY'), max(empno) empno
from emp
where empno > 0
( select /*+ QB_NAME(AV_SAL) */
deptno, avg(sal)
from emp
group by deptno ) y

Id | Operation | Name | Query Block
----------------------------------------------|--------------
1 | HASH JOIN | |
4 | VIEW | |
9 | VIEW | |
SEL$1
SEL$1
AV_SAL
AV_SAL
AV_SAL
AV_SAL
SEL$1
YR_HIRE
YR_HIRE
YR_HIRE
YR_HIRE
146

SQL> alter session set
2 events = '10053 trace name context forever, level 1';
Session altered.
148

**************************
Query transformations (QT)
**************************
CBQT: Validity checks passed for 7jpzpr2475cqw.
CSE: Sub-expression elimination in query block SEL$1 (#0)
*************************
Common Subexpression elimination (CSE)
*************************
CSE: CSE not performed on query block YR_HIRE (#0).
CSE: Sub-expression elimination in query block AV_SAL (#0)
CSE: CSE not performed on query block AV_SAL (#0).
CSE: CSE not performed on query block SEL$1 (#0).
***************************
Order-by elimination (OBYE)
***************************
OBYE: Considering Order-by Elimination from view SEL$1 (#0)
149

*********************************
Number of join permutations tried: 1
*********************************
GROUP BY adjustment factor: 1.000000
GROUP BY cardinality: 3.000000, TABLE cardinality: 14.000000
SORT ressource Sort statistics
Sort width: 598 Area size: 1048576 Max Area: 104857600
Degree: 1
Blocks to Sort: 1 Row size: 18 Total Rows: 14
Initial runs: 1 Merge passes: 0 IO Cost / pass: 0
Total IO sort cost: 0 Total CPU sort cost: 14312402
Total Temp space used: 0
Trying or-Expansion on query block AV_SAL (#3)
Transfer Optimizer annotations for query block AV_SAL (#3)
GROUP BY adjustment factor: 1.000000
Final cost for query block AV_SAL (#3) - All Rows Plan:
Best join order: 1
Cost: 4.0029 Degree: 1 Card: 14.0000 Bytes: 98
Resc: 4.0029 Resc_io: 3.0000 Resc_cpu: 14352069
Resp: 4.0029 Resp_io: 3.0000 Resc_cpu: 14352069
150

152
select
/*+ QB_NAME(top)
INDEX(@yr_hire emp (empno))
FULL(@av_sal emp)
*/
INDEX(emp emp_ix)

"Employee salary list,
plus department total,
plus grand total"
155

SQL> select empno, ename, sal, deptno from emp
2 order by deptno;
EMPNO ENAME SAL DEPTNO
---------- ---------- ---------- ----------
7782 CLARK 2450 10
7839 KING 5000 10
7934 MILLER 1300 10
...
7900 JAMES 950 30
7698 BLAKE 2850 30
7654 MARTIN 1250 30
156
SQL> select deptno,
2 sum(sal)
3 from emp
4 group by deptno
5 order by deptno;
DEPTNO SUM(SAL)
---------- ----------
10 8750
20 10875
30 9400
SQL> select sum(sal) from emp;
SUM(SAL)
----------
29025

SQL> select empno, ename, sal, deptno from emp
2 order by deptno;
EMPNO ENAME SAL DEPTNO
---------- ---------- ---------- ----------
7782 CLARK 2450 10
7839 KING 5000 10
7934 MILLER 1300 10
...
7900 JAMES 950 30
7698 BLAKE 2850 30
7654 MARTIN 1250 30
158
SQL> select deptno,
2 sum(sal)
3 from emp
4 group by rollup(deptno)
5 order by deptno;
DEPTNO SUM(SAL)
---------- ----------
10 8750
20 10875
30 9400
29025

EMPNO SAL DEPTNO
---------- ---------- ----------
7782 2450 10
7839 5000 10
7934 1300 10
7566 2975 20
7902 3000 20
7876 1100 20
7369 800 20
160
DEPTNO SUM(SAL)
---------- ----------
10 8750
20 10875
30 9400
29025
7782 2450 10
7839 5000 10
7934 1300 10
7566 2975 20
10 8750

SQL> select deptno,
2 nvl2(rownum,max(empno),null) empno,
3 nvl2(rownum,max(ename),null) ename,
4 sum(sal)
5 from emp
6 group by rollup(deptno,rownum)
7 order by deptno,empno;
DEPTNO EMPNO ENAME SUM(SAL)
---------- ---------- ---------- ----------
10 7782 CLARK 2450
10 7839 KING 5000
10 7934 MILLER 1300
10 8750
20 7369 SMITH 800
20 7566 JONES 2975
...
30 7900 JAMES 950
30 9400
29025162

SQL> select deptno,job,sum(sal) from scott.emp
2 group by CUBE(deptno,job)
3 order by deptno,job;
DEPTNO JOB SUM(SAL)
---------- --------- ----------
10 CLERK 1300
10 MANAGER 2450
10 PRESIDENT 5000
10 8750
20 ANALYST 6000
20 CLERK 1900
20 MANAGER 2975
20 10875
30 CLERK 950
30 MANAGER 2850
30 SALESMAN 5600
30 9400
ANALYST 6000
CLERK 4150
MANAGER 8275
PRESIDENT 5000
SALESMAN 5600
29025
164

SQL> select deptno, job, mgr, sum(sal) from emp
2 group by grouping sets (
3 (deptno),
4 (job,mgr), () ) ;
DEPTNO JOB MGR SUM(SAL)
---------- --------- ---------- ----------
CLERK 7902 800
PRESIDENT 5000
CLERK 7698 950
CLERK 7788 1100
CLERK 7782 1300
SALESMAN 7698 5600
MANAGER 7839 8275
ANALYST 7566 6000
10 8750
20 10875
30 9400
29025
166

"Find 10 consecutive deposits in a
24 hour period, then
a withdrawal within three days of
the last deposit, at a different retail outlet"
173

ACCT TSTAMP TYP AMT LOC
---------- ------------------ --- ---------- ----
54261 25/01/13 17:20:55 Dep 100 Perth
54261 25/01/13 17:56:58 Dep 165 Perth
54261 26/01/13 11:24:14 Dep 30 Subiaco
54261 26/01/13 11:47:53 Dep 45 Guildford
54261 26/01/13 12:59:38 Dep 100 Claremont
54261 26/01/13 13:26:04 Dep 80 Perth
54261 26/01/13 14:41:09 Dep 50 Perth
54261 26/01/13 14:53:12 Dep 50 Nedlands
54261 26/01/13 15:15:05 Dep 50 Leederville
54261 26/01/13 15:51:17 Dep 50 Guildford
54261 26/01/13 16:15:02 Dep 120 Perth
54261 26/01/13 16:36:51 Dep 100 Perth
54261 26/01/13 16:55:09 Dep 100 Perth
54261 26/01/13 18:07:17 Wth -500 Nedlands
174

SQL> select acct, tstamp, wthd_tstamp, txn_type, amt
2 from account_txns
3 MATCH_RECOGNIZE
4 ( partition by acct
5 order by tstamp
6 measures
7 dep.tstamp dep_tstamp,
8 wthd.tstamp wthd_tstamp
9 all rows per match
10 pattern ( dep{10,} wthd )
11 define
12 dep as
13 txn_type = 'Dep',
14 wthd as
15 txn_type = 'Wth'
16 and last(dep.tstamp)-first(dep.tstamp) < interval '1' day
17 and wthd.tstamp - last(dep.tstamp) < interval '3' day
18 and wthd.location != last(dep.location)
19 )
177

180
"talking" to your database
... makes it faster

select prod_id, max(amount)
from stores st,
customers c,
sales s
where s.cust_id = c.cust_id(+)
and c.store_id = st.store_id
and s.amount > 10
group by prod_id
183
hash outer join ? nested loop ?
STORES first ?
sort merge ?

---------------------------------------------------
---------------------------------------------------
| 1 | HASH GROUP BY | | 100 |
|* 2 | HASH JOIN | | 990K |
| 3 | NESTED LOOPS SEMI | | 5000 |
| 4 | TABLE ACCESS FULL| CUSTOMERS | 5000 |
|* 5 | INDEX UNIQUE SCAN| STORE_IX | 50 |
|* 6 | TABLE ACCESS FULL | SALES | 990K |
---------------------------------------------------
184

185
can we do better ?
add indexes ?
rewrite query ?
result cache ?
materialized view ?

186
share your knowledge with the db
oc04.sql

rows to columns, colums to rows
189

"I need sales by product
for each quarter....now"
190

SQL> select product, trunc(txn_date,'Q') mth, sum(quantity) total
3 from SALES
4 group by product,trunc(txn_date,'Q')
5 order by 1,2;
PRODUCT MTH TOTAL
-------------------- --- ----------
CHAINSAW JAN 251473
CHAINSAW APR 254830
CHAINSAW JUL 251994
CHAINSAW OCT 243748
HAMMER JAN 249889
HAMMER APR 256566
HAMMER JUL 252992
HAMMER OCT 249104
SCREW DRIVER JAN 245988
SCREW DRIVER APR 249219
SCREW DRIVER JUL 252128
SCREW DRIVER OCT 244721
SPADE JAN 242434
SPADE APR 254090
SPADE JUL 259613
...
191

"That’s wrong!...surely you know
I wanted it ACROSS the page"
192

SQL> select *
2 from (select product,
3 trunc(txn_date,'Q') mth,
4 quantity
5 from sales )
6 pivot( sum(quantity) for mth in
7 ( 'JAN',
8 'APR',
9 'JUL',
10 'OCT') )
11 order by 1
12 /
PRODUCT 'JAN' 'APR' 'JUL' 'OCT'
-------------------- ---------- ---------- ---------- ----------
CHAINSAW 251473 254830 251994 243748
HAMMER 249889 256566 252992 249104
SCREW DRIVER 245988 249219 252128 244721
SPADE 242434 254090 259613 248428
WHEEL BARROW 243899 249327 252296 254137
196

"That’s wrong!...surely you know
I wanted it DOWN the page"
198

SQL> desc SALES_ACROSS
Name Null? Type
----------------------------- -------- -------------
PRODUCT VARCHAR2(20)
Q1 NUMBER
Q2 NUMBER
Q3 NUMBER
Q4 NUMBER
199

SQL> select *
2 from SALES_ACROSS
3 UNPIVOT
4 ( quantity for quarter in (Q1,Q2,Q3,Q4) )
5 /
PRODUCT QUARTER QUANTITY
-------------------- ------- ----------
CHAINSAW Q1 251473
CHAINSAW Q2 254830
CHAINSAW Q3 251994
CHAINSAW Q4 243748
HAMMER Q1 249889
HAMMER Q2 256566
HAMMER Q3 252992
HAMMER Q4 249104
SCREW DRIVER Q1 245988
...
column values
become "quantity"
column names
become "quarter"
201

elements must be known in advance
202

SQL> select
2 ( select dname
3 from dept
4 where deptno = e.deptno ) dname,
5 decode(empno, 7499,
6 ( select max(sal) from emp ),
7 -1)
8 from
9 ( select * from emp
10 where sal > 0 ) e
11 where
12 ( select max(hiredate) from emp ) < sysdate
13 /
scalar
anywhere an
expression could be
205

SQL> create or replace
2 function CALC_TAX(p int) return number is
3 begin
4 dbms_lock.sleep(1);
5 return p;
6 end;
7 /
Function created.
SQL> create table T
2 as select rownum r, mod(rownum,5) r1 from dual
Table created.
1,2,3,..., 30
0,1,2,3,4,0,1,2,3,4, ...
207

SQL> select r, calc_tax(r1) tax from T;
R TAX
---------- ----------
1 1
2 2
3 3
4 4
...
28 3
29 4
30 0
30 rows selected.
Elapsed: 00:00:30.01
208

SQL> select r,
2 ( select calc_tax(r1) from dual) as tax
3 from T;
R TAX
---------- ----------
1 1
2 2
...
28 3
29 4
30 0
30 rows selected.
Elapsed: 00:00:05.01
209

subquery caching
... any subquery
210

what about multiple values
211

SQL> select
2 empno,
3 ( select dname, loc, revenue
4 from dept
5 where deptno = e.deptno )
6 from EMP e;
( select dname, loc, revenue
*
ERROR at line 3:
ORA-00913: too many values
212

SQL> select
2 empno,
3 ( select dname
4 from dept
5 where deptno = e.deptno ) dname,
6 ( select loc
7 from dept
8 where deptno = e.deptno ) loc,
9 ( select revenue
10 from dept
11 where deptno = e.deptno ) rev
12 from EMP e;
EMPNO DNAME LOC REV
---------- -------------- ------------- ----------
7839 ACCOUNTING NEW YORK 10000
7698 SALES CHICAGO 30000
...
213

SQL> create type multi_attrib as object (
2 dname varchar2(10),
3 loc varchar2(10),
4 rev number );
5 /
Type created.
215

SQL> select empno,
2 x.attr.dname,
3 x.attr.loc,
4 x.attr.rev
5 from
6 (
7 select
8 empno,
9 ( select multi_attrib(dname,loc,revenue)
10 from dept
11 where deptno = e.deptno ) attr
12 from EMP e
13 ) x;
EMPNO ATTR.DNAME ATTR.LOC ATTR.REV
---------- ---------- ---------- ----------
7698 SALES CHICAGO 30000
216

SQL> select rpad(' ',level)||ename,
2 from emp
3 start with mgr is null
4 connect by prior empno = mgr
ENAME
---------------------------
KING
BLAKE
JAMES
ALLEN
WARD
CLARK
MILLER
220

SQL> select empno, ename, mgr
2 from emp
3 where mgr is null;
EMPNO ENAME MGR
---------- -------------------- ----------
7839 KING
221

SQL> select e2.empno, e2.ename, e2.mgr
2 from emp e2,
3 ( select empno, mgr
4 from emp
5 where mgr is null ) inner
6 where e2.mgr = inner.empno;
EMPNO ENAME MGR
---------- -------------------- ----------
7566 JONES 7839
7698 BLAKE 7839
7782 CLARK 7839
222

2 from emp e3,
3 ( select e2.empno, e2.ename, e2.mgr
4 from emp e2,
6 from emp
8 where e2.mgr = inner.empno ) inner
EMPNO ENAME MGR
---------- -------------------- ----------
7902 FORD 7566
7788 SCOTT 7566
7900 JAMES 7698
7844 TURNER 7698
7654 MARTIN 7698
7521 WARD 7698
7934 MILLER 7782
223

2 from emp e4,
4 from emp e3,
6 from emp e2,
8 from emp
EMPNO ENAME MGR
---------- -------------------- ----------
7876 ADAMS 7788
recursive...
224

SQL> with EACH_LEVEL (empno, name, mgr) as
2 ( --
3 -- start with
4 --
5 select empno, ename, mgr
6 from emp
7 where mgr is null
8 --
9 -- connect by
10 --
11 union all
12 select emp.empno, emp.ename, emp.mgr
13 from emp, EACH_LEVEL
14 where emp.mgr = each_level.empno
15 )
16 select *
17 from each_level;
227

EMPNO NAME MGR
---------- --------------- ----------
7839 KING
7566 JONES 7839
7698 BLAKE 7839
7782 CLARK 7839
7499 ALLEN 7698
7521 WARD 7698
7654 MARTIN 7698
7788 SCOTT 7566
7844 TURNER 7698
7900 JAMES 7698
7902 FORD 7566
7934 MILLER 7782
7369 SMITH 7902
7876 ADAMS 7788
228

with RECURSIVE_WITH (c1,c2,c3) as
(
<starting/entry point>
union all
<recursive relationship>
)
select ...
from RECURSIVE_WITH
230

you control pseudo-functions
231

SQL> with each_level (empno, name, mgr, rlevel) as
2 ( select empno, ename, mgr, 1 rlevel
3 from emp
4 where mgr is null
5 union all
6 select emp.empno, emp.ename, emp.mgr, rlevel+1
7 from emp, each_level
9 )
10 select * from each_level;
EMPNO NAME MGR RLEVEL
---------- --------------- ---------- ----------
7839 KING 1
7566 JONES 7839 2
7698 BLAKE 7839 2
7782 CLARK 7839 2
7499 ALLEN 7698 3
...
232

SQL> with each_level (empno, name) as
2 ( select empno, ename from emp
3 where mgr is null
4 union all
5 select e.empno,
6 each_level.name||'-'||e.ename
7 from emp e, each_level
8 where e.mgr = each_level.empno
9 )
10 select empno, name from each_level;
EMPNO NAME
---------- --------------------------------
7839 KING
7566 KING-JONES
7698 KING-BLAKE
7782 KING-CLARK
7499 KING-BLAKE-ALLEN
7521 KING-BLAKE-WARD
...233

SQL> with each_level (empno, name, mgr) as
2 ( select empno, ename, mgr
3 from emp
4 where ename = 'KING'
5 union all
9 )
10 select *
11 from each_level;
ERROR:
ORA-32044: cycle detected while executing recursive WITH query
235

SQL> with each_level (empno, name, mgr) as
2 ( select empno, ename, mgr from emp
4 union all
7 where emp.mgr = each_level.empno )
8 CYCLE mgr SET is_cycle TO 'Y' DEFAULT 'N'
9 select * from each_level;
EMPNO NAME MGR IS_CYCLE
---------- ---------- ---------- ----------
7839 KING 7499 N
7566 JONES 7839 N
7521 WARD 7698 N
7839 KING 7499 Y
7876 ADAMS 7788 N
...
236

SQL> with each_level (empno, name, hiredate, mgr) as
2 ( select empno, ename, hiredate, mgr from emp
4 union all
5 select e.empno,
6 each_level.name||'-'||e.ename, e.hiredate, e.mgr
8 where e.mgr = each_level.empno )
9 SEARCH BREADTH FIRST BY HIREDATE SET IDX
10 select name, hiredate, idx from each_level;
NAME HIREDATE IDX
-------------------------------- --------- ----------
KING 17-NOV-81 1
KING-JONES 02-APR-81 2
KING-BLAKE 01-MAY-81 3
KING-CLARK 09-JUN-81 4
KING-BLAKE-ALLEN 20-FEB-81 5
KING-BLAKE-WARD 22-FEB-81 6
...
KING-JONES-FORD-SMITH 17-DEC-80 13
KING-JONES-SCOTT-ADAMS 23-MAY-87 14
238

SQL> with each_level (empno, name, hiredate, mgr) as
2 ( select empno, ename, hiredate, mgr from emp
4 union all
5 select e.empno,
6 each_level.name||'-'||e.ename, e.hiredate, e.mgr
8 where e.mgr = each_level.empno )
9 SEARCH DEPTH FIRST BY HIREDATE SET IDX
10 select name, hiredate, idx from each_level;
NAME HIREDATE IDX
-------------------------------- --------- ----------
KING 17-NOV-81 1
KING-JONES 02-APR-81 2
KING-JONES-FORD 03-DEC-81 3
KING-JONES-FORD-SMITH 17-DEC-80 4
KING-JONES-SCOTT 19-APR-87 5
KING-JONES-SCOTT-ADAMS 23-MAY-87 6
KING-BLAKE 01-MAY-81 7
KING-BLAKE-ALLEN 20-FEB-81 8
etc
239

SQL> select * from messages;
TXT
----------------------------------------------------------
I caught up with Connor and Maria Colgan today. They have
taken over AskTOM for Oracle Developers
242

SQL> select * from twitter_handles;
ID TERM HANDLE
---- ------------------------------ ---------------
1 Connor McDonald @connor_mc_d
2 Connor @connor_mc_d
3 Maria Colgan @sqlmaria
4 Oracle Developers @otndev
5 Oracle @oracle
6 AskTOM @oracleasktom
243

SQL> with
2 tweetised(ind,tweet_txt) as
3 (
4 select 1 ind, txt tweet_txt
5 from messages
6 union all
7 select ind+1, replace(tweet_txt,term,handle)
8 from tweetised, twitter_handles
9 where ind = id
10 )
11 select * from tweetised;
244

IND TWEET_TXT
--------- -----------------------------------------------------------------------------------------
1 I caught up with Connor and Maria Colgan today. They have taken over AskTOM for...
2 I caught up with Connor and Maria Colgan today. They have taken over AskTOM for...
3 I caught up with @connor_mc_d and Maria Colgan today. They have taken over AskTOM for...
4 I caught up with @connor_mc_d and @sqlmaria today. They have taken over AskTOM for ...
5 I caught up with @connor_mc_d and @sqlmaria today. They have taken over AskTOM for @otndev
6 I caught up with @connor_mc_d and @sqlmaria today. They have taken over AskTOM for @otndev
7 I caught up with @connor_mc_d and @sqlmaria today. They have taken over @oracleasktom ...
245

SQL> with
2 tweetised(ind,tweet_txt) as
3 (
4 select 1 ind, txt tweet_txt
5 from messages
6 union all
7 select ind+1, replace(tweet_txt,term,handle)
8 from tweetised, twitter_handles
9 where ind = id
10 )
11 select * from tweetised
12 order by ind desc
13 fetch first 1 row only;
IND TWEET_TXT
---------- ------------------------------------------------------
7 I caught up with @connor_mc_d and @sqlmaria today. They...
246

251
SQL> select dt, val
2 from t
3 order by dt;
DT VAL
--------- ----------
02-JAN-11 195
03-JAN-11
04-JAN-11
05-JAN-11
06-JAN-11 129
07-JAN-11
08-JAN-11
09-JAN-11
10-JAN-11 87
11-JAN-11
...
195
195
195
129
129
129
87

252
SQL> select dt, val,
2 case when val is not null
3 then to_char(row_number() over (order by dt),'fm0000')||'-'||val
4 end max_val
5 from t
6 order by dt;
DT VAL MAX_VAL
--------- ---------- -----------
02-JAN-11 195 0001-195
03-JAN-11
04-JAN-11
05-JAN-11
06-JAN-11 129 0005-129
07-JAN-11
08-JAN-11
09-JAN-11
10-JAN-11 87 0009-87
11-JAN-11
...

253
2 max(max_val) over (order by dt) max_val_str
3 from ( select dt, val,
5 then to_char(row_number() over (order by dt),'fm0000')||'-'||val
6 end max_val
7 from t ) order by dt;
DT VAL MAX_VAL_STR
--------- ---------- ------------------
02-JAN-11 195 0001-195
03-JAN-11 0001-195
04-JAN-11 0001-195
05-JAN-11 0001-195
06-JAN-11 129 0005-129
07-JAN-11 0005-129
08-JAN-11 0005-129
09-JAN-11 0005-129
10-JAN-11 87 0009-87
11-JAN-11 0009-87
...

254
2 to_number(substr(max(max_val) over (order by dt),5)) max_val
3 from ( select dt, val,
5 then to_char(row_number() over (order by dt),'fm0000')||val
6 end max_val
7 from t ) order by dt
8 /
DT VAL MAX_VAL
--------- ---------- ----------
02-JAN-11 195 195
03-JAN-11 195
04-JAN-11 195
05-JAN-11 195
06-JAN-11 129 129
07-JAN-11 129
08-JAN-11 129
09-JAN-11 129
10-JAN-11 87 87
11-JAN-11 87

255
2 last_value(val ignore nulls) over (order by dt) val
3 from t
4 order by dt;
DT VAL VAL
--------- ---------- ----------
02-JAN-11 195 195
03-JAN-11 195
04-JAN-11 195
05-JAN-11 195
06-JAN-11 129 129
07-JAN-11 129
08-JAN-11 129
09-JAN-11 129
10-JAN-11 87 87
11-JAN-11 87

defacto language polyglot world
260

SQL>
Connected.
SQL>
ORACLE instance shut down.
SQL>
conn / as sysdba
shutdown abort
@connor_mc_d

#MakeSQLGreatAgain
@connor_mc_d

SQL techniques for faster applications

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