I Have a table emp which has
ename sal
Smith 1000
Mark 2000
Jack 500
The output should be(person earning lower salary on the left)
Jack Smith
Jack Mark
Smith Mark
Please help
Seems like a cross join with a filter.
select h1.ename as first, h2.ename as second
from have as h1
cross join have as h2
where h1.sal>h2.sal
Related
I would like to compare two SQL statements which produce the same result. For example
SELECT
id, name,
(SELECT street || ' ' || town from addresses WHERE addresses.id=customers.addressid) AS address
FROM customers;
-- vs
SELECT
id, name,
street || ' ' || town AS address
FROM customers c LEFT JOIN addresses a ON c.id=a.customerid;
Here I want to compare the performance of the subquery compared to using a join. I know about the other advantages and disadvantages of subqueries and joins, but I’m more interested in comparing their performance.
How can I do a performance comparison? Is there some sort of timing test?
Is there some sort of timing test?
Yes, in SQL*Plus, do it as
SQL> set timing on
and then run queries, each of them several times (to avoid caching issues) and compare time needed for each query to complete. Note that on small data sets you won't notice any difference, so - whichever you use, it'll be OK.
SQL> select e.deptno, (select d.dname from dept d where d.deptno = e.deptno) dname, e.ename
2 from emp e
3 where e.deptno = 20;
DEPTNO DNAME ENAME
---------- -------------- ----------
20 RESEARCH SMITH
20 RESEARCH JONES
20 RESEARCH SCOTT
20 RESEARCH ADAMS
20 RESEARCH FORD
Elapsed: 00:00:00.04
SQL> select e.deptno, d.dname, e.ename
2 from emp e join dept d on e.deptno = d.deptno
3 where e.deptno = 20;
DEPTNO DNAME ENAME
---------- -------------- ----------
20 RESEARCH SMITH
20 RESEARCH JONES
20 RESEARCH SCOTT
20 RESEARCH ADAMS
20 RESEARCH FORD
Elapsed: 00:00:00.03
SQL>
Other than that, did you compare explain plans? Did you collect statistics on tables and indexes (and do it regularly)? Are there any indexes (should be on columns used in joins, most probably)?
I have tried the following query but I still get this error and I am not able to find a solution to resolve it. I want to be able to get one of the three dates (LOAD,LAST_MODIFIED,ORDER_ITEM_LAST_UPDATE) according to the situation. However, I need also to use the actual calendar date to use a specific column inside. It is why I do the join (+) with the LOAD_DATE. Now, I try to find a way not to get the error ORA-01719, Someone can help me?
ORA-01719: outer join operator (+) not allowed in operand of OR or IN
01719. 00000 - "outer join operator (+) not allowed in operand of OR or IN"
*Cause: An outer join appears in an or clause.
*Action: If A and B are predicates, to get the effect of (A(+) or B),
try (select where (A(+) and not B)) union all (select where (B)).
Error at Line: 17 Column: 35
CODE:
SELECT A.PRODUCT_ID AS KEY,
TO_CHAR(A.ORDER_DATE, 'MM/DD/YYYY') AS ORDER_CREATION_DATE,
TO_CHAR(B.LOAD_DATE, 'MM/DD/YYYY') AS LOAD_DATE,
TO_CHAR(B.LAST_MODIFIED_DATE, 'MM/DD/YYYY') AS LAST_MODIFIED_DATE,
TO_CHAR(B.ORDER_ITEM_LAST_UPDATED, 'MM/DD/YYYY') AS ORDER_ITEM_LAST_UPDATED,
A.ORDER_STATUS AS ORDER_STATUS,
A.ORDER_ITEM_STATUS AS ORDER_ITEM_STATUS,
A.ORDER_ACTION AS ORDER_ACTION,
NVL(B.ORDER_ITEM_ACTION, 'NOT APPLICABLE') AS ORDER_ITEM_ACTION,
NVL(B.CEASE_REASON, 'NOT APPLICABLE') AS ORDER_CEASE_REASON,
A.PRO_SYSTEM AS PRO_SYSTEM,
CASE WHEN (A.PRO_SYSTEM = 'X') THEN 'Y' ELSE 'Z' END AS FLOW
FROM PART1 A, PART2 B,DATA_REP_CALENDAR CAL
WHERE A.ORDER_SEQ = B.ORDER_SEQ
AND TRUNC(B.LOAD_DATE) = CAL.ACTUAL_CALENDAR_DATE (+)
AND TRUNC(B.LOAD_DATE) BETWEEN ADD_MONTHS( TO_DATE('07/01/2019', 'MM/DD/YYYY'),- 6) and LAST_DAY( TO_DATE('07/01/2019', 'MM/DD/YYYY'))
OR TRUNC(B.LAST_MODIFIED_DATE) BETWEEN ADD_MONTHS( TO_DATE('07/01/2019', 'MM/DD/YYYY'),- 6) and LAST_DAY( TO_DATE('07/01/2019', 'MM/DD/YYYY'))
OR TRUNC(B.ORDER_ITEM_LAST_UPDATED) BETWEEN ADD_MONTHS( TO_DATE('07/01/2019', 'MM/DD/YYYY'),- 6) and LAST_DAY( TO_DATE('07/01/2019', 'MM/DD/YYYY'));
A simple example based on Scott's EMP and DEPT tables; there's department 40, and nobody works in it. If you want to display it (while joining those tables), use outer join. The "old" Oracle outer join operator is (+) which has its ... drawbacks. If you use outer join, many things (that won't work with (+)) will now work.
This is what you have now:
SQL> select d.deptno, d.dname, e.ename
2 from dept d,
3 emp e
4 where d.deptno = e.deptno (+)
5 order by d.deptno, e.ename;
DEPTNO DNAME ENAME
---------- -------------- ----------
10 ACCOUNTING CLARK
10 ACCOUNTING KING
10 ACCOUNTING MILLER
20 RESEARCH ADAMS
20 RESEARCH FORD
20 RESEARCH JONES
20 RESEARCH SCOTT
20 RESEARCH SMITH
30 SALES ALLEN
30 SALES BLAKE
30 SALES JAMES
30 SALES MARTIN
30 SALES TURNER
30 SALES WARD
40 OPERATIONS
15 rows selected.
SQL>
This is how you should rewrite it:
SQL> select d.deptno, d.dname, e.ename
2 from dept d left join emp e on e.deptno = d.deptno
3 order by d.deptno, e.ename;
DEPTNO DNAME ENAME
---------- -------------- ----------
10 ACCOUNTING CLARK
10 ACCOUNTING KING
10 ACCOUNTING MILLER
20 RESEARCH ADAMS
20 RESEARCH FORD
20 RESEARCH JONES
20 RESEARCH SCOTT
20 RESEARCH SMITH
30 SALES ALLEN
30 SALES BLAKE
30 SALES JAMES
30 SALES MARTIN
30 SALES TURNER
30 SALES WARD
40 OPERATIONS
15 rows selected.
SQL>
I need to modify my script using rowcount to check if the data in table or not?. Here, i write the query to select a data for last 5 days from current system date. But sometimes there is no data in table for 5 days. So i need to fetch for 10 day or more.
Query:
Select ep.ENTERPRISE_NAME||'|'||s.id||'|'||s.SUBMISSION_DATE||'|'||E.VALUE
from JOB_SUMMARY_EXT e, ob_summary s, enterprise ep
where e.id = s.id and e.name_res_key = 'Model'
and s.job_id in (select id from job_summary where
trunc(start_date) > trunc(sysdate) -10 and service_name ='Model2' )
I don't know how to modify my Query using rowcount. If rowcount is 0 then i want select data for 10 days.Otherwise it should to fetch for 5 days automatically. I want this to be done as single query.
It looks that you want to select the last 5 "days" from that table. So, why would you anchor to SYSDATE if there aren't rows for each of those days? I'd suggest another approach: literally, select last 5 days. Here's how.
As I don't have your tables, I'm using Scott's EMP table which contains information about employees. It is an ancient one so HIREDATE column is set to 1980s, but never mind that. Sorting employees by HIREDATE in descending order shows:
SQL> alter session set nls_date_format = 'dd.mm.yyyy';
Session altered.
SQL> select ename, hiredate from emp order by hiredate desc;
ENAME HIREDATE
---------- ----------
ADAMS 12.01.1983 1.
SCOTT 09.12.1982 2.
MILLER 23.01.1982 3.
FORD 03.12.1981 4.
JAMES 03.12.1981 4.
KING 17.11.1981 5. --> I want to fetch rows up to KING
MARTIN 28.09.1981
TURNER 08.09.1981
CLARK 09.06.1981
BLAKE 01.05.1981
JONES 02.04.1981
WARD 22.02.1981
ALLEN 20.02.1981
SMITH 17.12.1980
14 rows selected.
SQL>
As you can see, the 4th date is shared by two employees so I want to include them both. DENSE_RANK analytic function helps:
SQL> with last5 as
2 (select ename,
3 job,
4 sal,
5 hiredate,
6 dense_rank() over (order by hiredate desc) rnk
7 from emp
8 )
9 select ename, job, sal, hiredate
10 from last5
11 where rnk <= 5;
ENAME JOB SAL HIREDATE
---------- --------- ---------- ----------
ADAMS CLERK 1100 12.01.1983
SCOTT ANALYST 3000 09.12.1982
MILLER CLERK 1300 23.01.1982
JAMES CLERK 950 03.12.1981
FORD ANALYST 3000 03.12.1981
KING PRESIDENT 5000 17.11.1981
6 rows selected.
SQL>
What does it do? The LAST5 CTE sorts employees (as above), DENSE_RANK ranks them; finally, the last SELECT (which begins at line #9) fetches desired rows.
In your case, that might look like this:
with last5 as
(select id,
dense_rank() over (order by start_date desc) rnk
from job_summary
where service_name = 'Model2'
)
select ep.enterprise_name,
s.id,
s.submission_date,
e.value
from job_summary_ext e
join ob_summary s on e.id = s.id
join last5 t on t.id = s.id
join enterprise ep on <you're missing join condition for this table>
where e.name_res_key = 'Model';
Note that you're missing join condition for the ENTERPRISE table; if that's really so, no problem - you'd use cross join for that table, but I somehow doubt that you want that.
Finally, as you use SQL*Plus, perhaps you don't need to concatenate all columns and separate them by the pipe | sign - set it as a column separator, e.g.
SQL> set colsep '|'
SQL>
SQL> select deptno, dname, loc from dept;
DEPTNO|DNAME |LOC
----------|--------------|-------------
10|ACCOUNTING |NEW YORK
20|RESEARCH |DALLAS
30|SALES |CHICAGO
40|OPERATIONS |BOSTON
SQL>
If you want to
return 10 last days if select count(*) returns 0, or
return 5 last days if select count(*) returns a positive number
then something like this might help (again based on Scott's EMP table):
with
tcnt as
-- count number of rows; use your own requirement, I'm checking
-- whether someone got hired today. In Scott's EMP table, nobody was
-- so CNT = 0
(select count(*) cnt
from emp
where hiredate >= trunc(sysdate)
)
select e.ename, e.job, e.sal, e.hiredate
from emp e cross join tcnt c
where e.hiredate >= case when c.cnt = 0 then trunc(sysdate) - 10
else trunc(sysdate) - 5
end;
Apply it to your tables; I don't know which of those 3 tables' count you want to check.
Tried to add in comments but it was too long for comments and Not clear on count based on but here is case in where clause substitute your count statement with nvl function
SELECT ep.ENTERPRISE_NAME||'|'||s.id||'|'||s.SUBMISSION_DATE||'|'||E.VALUE
FROM JOB_SUMMARY_EXT e,
ob_summary s,
enterprise ep
WHERE e.id = s.id
AND e.name_res_key = 'Model'
AND s.job_id IN
(SELECT id
FROM job_summary
WHERE service='Model'
AND trunc(start_date) >
CASE WHEN
(WRITE your SELECT COUNT criteria WITH NVL FUNCTION)<=0 THEN
trunc(sysdate) -10
ELSE trunc(sysdate)-5
END )
Source Table: EMP_LOCATION
NAME LOCATION
-------------------------------
SMITH NY;CA;IL;GA
JAMES MO;AZ;RI
FORD NJ
SCOTT TX;VA;WA;NH
MARTIN MD;CT
Required Output:
NAME LOCATION
-------------------
FORD NJ
JAMES AZ
JAMES MO
JAMES RI
MARTIN CT
MARTIN MD
SCOTT NH
SCOTT TX
SCOTT VA
SCOTT WA
SMITH CA
SMITH GA
SMITH IL
SMITH NY
Some people will ask you to show some code, but when I needed this I spent a lot of time creating a function then I realize that I could do it with a connect by. So what you need is this:
SELECT name, REGEXP_SUBSTR (location, '[^;]+', 1, LEVEL) AS location
FROM emp_location
CONNECT BY
LEVEL <= LENGTH(REGEXP_REPLACE (location, '[^;]*')) + 1
GROUP BY name, REGEXP_SUBSTR (location, '[^;]+', 1, LEVEL)
ORDER BY name
I was given a query to explain. Could someone please explain it to me:
select j.ip_num from
jobs j, address a
where j.jobtype='C' and
a.sel_code(+)='H' and
j.ip_num=a.ip_num and
a.ip_num is null order by a.ip_num
That query selects every JOB.IP_NUM which doesn't have a matching ADDRESS record or where the matching ADDRESS record has a SEL_CODE not equal to 'H'.
The (+) is Oracle's old outer join syntax. It is the only OUTER JOIN syntax supported in versions of Oracle before 9i.
In this query we get one row for every row in EMP which matches a department, plus a row for the DEPTNO=40, which has no employees:
SQL> select d.dname
2 , e.ename
3 from dept d
4 , emp e
5 where d.deptno = e.deptno(+)
6 /
DNAME ENAME
-------------- ----------
ACCOUNTING SCHNEIDER
ACCOUNTING BOEHMER
ACCOUNTING KISHORE
RESEARCH ROBERTSON
RESEARCH KULASH
RESEARCH GASPAROTTO
RESEARCH RIGBY
RESEARCH CLARKE
SALES HALL
SALES CAVE
SALES SPENCER
SALES BILLINGTON
SALES PADFIELD
SALES VAN WIJK
SALES KESTELYN
SALES LIRA
OPERATIONS PSMITH
HOUSEKEEPING VERREYNNE
HOUSEKEEPING FEUERSTEIN
HOUSEKEEPING PODER
HOUSEKEEPING TRICHLER
COMMUNICATIONS
22 rows selected.
SQL>
Now, if we put an additional filter on the EMP table like this, we simply get one record for each Department, because only one record in EMP now matches:
SQL> select d.dname
2 , e.ename
3 from dept d
4 , emp e
5 where d.deptno = e.deptno(+)
6 and e.ename(+) = 'CAVE'
7 /
DNAME ENAME
-------------- ----------
ACCOUNTING
RESEARCH
SALES CAVE
OPERATIONS
HOUSEKEEPING
COMMUNICATIONS
6 rows selected.
SQL>
/
To convert this query into the ANSI SQL syntax we have to do this:
SQL> select d.dname
2 , e.ename
3 from dept d
4 left outer join emp e
5 on ( d.deptno = e.deptno
6 and e.ename = 'CAVE' )
7 /
DNAME ENAME
-------------- ----------
ACCOUNTING
RESEARCH
SALES CAVE
OPERATIONS
HOUSEKEEPING
COMMUNICATIONS
6 rows selected.
SQL>
Note that if we don't include the additonal clause in the JOIN but leave it in the WHERE clause we get a different result:
SQL> select d.dname
2 , e.ename
3 from dept d
4 left outer join emp e
5 on ( d.deptno = e.deptno )
6 where e.ename = 'CAVE'
7 /
DNAME ENAME
-------------- ----------
SALES CAVE
SQL>
This is the equivalent of omitting the (+) in the second old skool query.
The query is joining the 2 tables jobs, and address. These tables are joining on the field ip_num but you are looking for the records that exist in the jobs table but do not exist in the address table.
This is a LEFT OUTER JOIN. This query could also be written
SELECT j.ip_num
FROM jobs j
LEFT OUTER JOIN address a
ON j.ip_num=a.ip_num
WHERE j.jobtype='C' AND
a.sel_code(+)='H' AND
a.ip_num is null
ORDER BY a.ip_num
It might be useful to see a visual picture joins http://www.codinghorror.com/blog/2007/10/a-visual-explanation-of-sql-joins.html