How to hide rows where aggregate functions are used - sql

let’s imagine here is my report:
select 1 from dual
union all
select 2 from dual
union all
select 3 from dual
union all
select 4 from dual
Output:
1
2
3
4
If e.g. i want to hide part of the report in an easy way I simply add 1 = 2 to where clause:
select 1 from dual
union all
select 2 from dual
union all
select 3 from dual where 1 = 2
union all
select 4 from dual
Output:
1
2
4
Cool! However, when select uses aggregate functions, this trick does not help. The row is generated anyway:
select 1 from dual
union all
select 2 from dual
union all
select max(3) from dual where 1 = 2
union all
select 4 from dual
Output:
1
2
(null)
4
Someone maybe know a simple, easy way to hide such rows?


An aggregation query with no group by always returns exactly one row -- even if no rows are being aggregated.
You want to filter after the aggregation, so use having:
select max(3) from dual having 1 = 2

Related

using regular expression that not include string '05613'. have NAW_05613_11_PL04_02 in table. need condition rows which have 05613 not be displayed

I want to fetch data from database using regular expression which should not include string '05613'.
I have values like NAW_05613_11_PL04_02 in my table. I want to give condition that all rows which have 05613 in it should not be displayed.
I have tried using REGEXP_LIKE(d.variable_value_string, '^N(*)[^{05613}](*)')
SELECT * from tablename where REGEXP_LIKE(columnname, '^N(*)[^{05613}](*)')
Expected result should be- row with value having 05613 should not be retrieved.

A simple LIKE could be enough:
... columnName not like '%05613%'
For example:
SQL> with test(c) as (
2 select '05613XX' from dual union all
3 select 'XX05613' from dual union all
4 select 'X05613X' from dual union all
5 select 'XXX' from dual
6 )
7 select *
8 from test
9 where c not like '%05613%';
C
-------
XXX
SQL>
If you need, for some reason, regexp_like, this is a way:
SQL> with test(c) as (
2 select '05613XX' from dual union all
3 select 'XX05613' from dual union all
4 select 'XX05613' from dual union all
5 select 'X05613X' from dual union all
6 select 'XXX' from dual
7 )
8 select *
9 from test
10 where not regexp_like(c, '05613');
C
-------
XXX

If this is your assignment and usage of regexp_like is mandated then use following regexp_like:
SELECT * from tablename D
where Not REGEXP_LIKE(d.variable_value_string, '05613')
Cheers!!

Always show a value highst when sorting

I Oracle, I have a table with following values
1
2
4
10
I always want 2 to show up highest following by all other values in DESCending order, as follows :
2
10
4
1

You can order by a value you build with a case; for example:
with tab(col) as (
select 1 from dual union all
select 2 from dual union all
select 4 from dual union all
select 10 from dual
)
select col
from tab
order by case when col = 2 then 1 else 2 end asc,
col desc
gives:
COL
----------
2
10
4
1

try like below if column is not null
with tab(col) as (
select 1 from dual union all
select 2 from dual union all
select 4 from dual union all
select 10 from dual
)
select col
from tab
ORDER BY NULLIF(col, 2) desc NULLS FIRST
output
COL
2
10
4
1
demo link

Usage of combinatorics in Oracle SQL

Could use some help or insights, cause I'm going nuts..
Situation: I have a table of players ID's, with values 1,2,3.. to 7.
Objective: Want to create a roster of 4 players, from available players (in our case there are 7 of them). Its a classical combinatoric task, we need to calculate C(k,n). In our case C(4,7)=840/24=35. So, there are possible 35 ways to build a roster. I want to create a table of rosters with player ID's. Here's the current script, that builds the current roster table:
with comb_tbl as(
select
tmp_out.row_num,
regexp_substr(tmp_out.comb_sets,'[^,]+',1,1) plr_id_1,
regexp_substr(tmp_out.comb_sets,'[^,]+',1,2) plr_id_2,
regexp_substr(tmp_out.comb_sets,'[^,]+',1,3) plr_id_3,
regexp_substr(tmp_out.comb_sets,'[^,]+',1,4) plr_id_4
from(
select
rownum row_num,
substr(tmp.combinations,2) comb_sets
from(
select
sys_connect_by_path(plr.plr_id, ',') combinations
from(
select 1 plr_id from dual union
select 2 plr_id from dual union
select 3 plr_id from dual union
select 4 plr_id from dual union
select 5 plr_id from dual union
select 6 plr_id from dual union
select 7 plr_id from dual) plr
connect by nocycle prior plr.plr_id != plr.plr_id) tmp
where
length(substr(tmp.combinations,2)) = 7) tmp_out)
select
tmp1.*
from
comb_tbl tmp1
Problem:Its creates 840 possibilities, but I need to remove the "identical" ones, for example roster (1,2,3,4) is "identical" to roster (2,1,3,4). Any insights/comments/critics are welcome. Maybe the approach itself is wrong?

There is a 1-1 correspondence between possible rosters and ORDERED subsets of four elements of the seven-element set.
In your CONNECT BY clause, you only check that the player id's be different, rather than that they be in increasing order. Change != to < in CONNECT BY and it will work. (Also, you won't need NOCYCLE anymore.)

This could be a join way:
with plr(plr_id) as
( select level from dual connect by level <= 7)
select p1.plr_id, p2.plr_id, p3.plr_id, p4.plr_id
from plr p1
inner join plr p2
on(p1.plr_id < p2.plr_id)
inner join plr p3
on(p2.plr_id < p3.plr_id)
inner join plr p4
on(p3.plr_id < p4.plr_id)
For example, with n=5 you would have:
PLR_ID PLR_ID PLR_ID PLR_ID
---------- ---------- ---------- ----------
1 2 3 4
1 2 3 5
1 2 4 5
1 3 4 5
2 3 4 5

This is not an answer; it's merely a continuation of my earlier comment:
By making those additional changes, your query could end up something like:
SELECT regexp_substr(tmp_out.comb_sets,'[^,]+',1,1) plr_id_1,
regexp_substr(tmp_out.comb_sets,'[^,]+',1,2) plr_id_2,
regexp_substr(tmp_out.comb_sets,'[^,]+',1,3) plr_id_3,
regexp_substr(tmp_out.comb_sets,'[^,]+',1,4) plr_id_4
FROM (SELECT sys_connect_by_path(plr.plr_id, ',') comb_sets,
LEVEL lvl
FROM (select 1 plr_id from dual union all
select 2 plr_id from dual union all
select 3 plr_id from dual union all
select 4 plr_id from dual union all
select 5 plr_id from dual union all
select 6 plr_id from dual union all
select 7 plr_id from dual) plr
CONNECT BY PRIOR plr.plr_id < plr.plr_id
AND LEVEL <= 4) tmp_out
WHERE lvl = 4;
which is, IMO, easier to read and understand than your original query.

Want a SQL to group values by value scope in oracle

I have a table t1 and there is a column named days, so I want to group the days by 1 to 5 days and 6-15 days and more than 15 days then calculate the count for each group, but I don't know how to write the sql, can anyone tell me? the result should be looked like below:
Number Scope(days)
5 1-5
7 6-15
10 15+

If I understand well, this could be a way:
with t1(days) as (
select 1 from dual union all
select 2 from dual union all
select 5 from dual union all
select 6 from dual union all
select 7 from dual union all
select 8 from dual union all
select 10 from dual union all
select 11 from dual union all
select 16 from dual union all
select 17 from dual union all
select 19 from dual union all
select 19 from dual
)
/* the query */
select count(*),
case
when days between 1 and 5 then '1-5'
when days between 6 and 15 then '6-15'
else '+15'
end
from t1
group by case
when days between 1 and 5 then '1-5'
when days between 6 and 15 then '6-15'
else '+15'
end
that gives:
COUNT(*) CASE
---------- ----
3 1-5
4 +15
5 6-15
The idea is to aggregate by something that say the "group" where every number is, and you can easily build such an information with a CASE.
Accordin to Jarlh's suggestion, this can be re-written as
select count(*), the_group
from (
select case
when days between 1 and 5 then '1-5'
when days between 6 and 15 then '6-15'
else '+15'
end the_group
from t1
)
group by the_group
This obviously assumes that you only have positive numbers.

Select values is a row as column values

How can I retrieve values in a row as column values?
Example:
Consider the output of below query as INPUT :
Select 1,2,3,4,5,6,7,8,9,10
from dual;
I need a query that can give below output:
COL1
----
1
2
3
4
5
6
7
8
9
10

SELECT 1 AS "COL1" FROM dual
UNION
SELECT 2 FROM dual
UNION
SELECT 3 FROM dual
UNION
SELECT 4 FROM dual
UNION
SELECT 5 FROM dual
UNION
SELECT 6 FROM dual
UNION
SELECT 7 FROM dual
UNION
SELECT 8 FROM dual
UNION
SELECT 9 FROM dual
UNION
SELECT 10 FROM dual ;

If you want to generate a sequence of numbers in Oracle:
with n as (
select level as n
from dual
connect by level <= 10
)
select *
from n;
Or, if you have 10 columns, you can do an unpivot. An easy way is with union all:
select col1 from t union all
select col2 from t union al
. . .
select col10 from t;