I have a need to perform MINUS operation between two similar tables, count the resulting rows and check if the count is equal to zero all in a SQL statement.
I have done the following but i am not sure about how to compare it to zero.
select count(*) from(select * from table1 MINUS SELECT * FROM table2)
Something like this?
SQL> with t_minus as
2 (select deptno from emp
3 minus
4 select deptno from dept
5 )
6 select case when count(*) = 0 then 'it is zero'
7 else 'it is not zero'
8 end result
9 from t_minus;
RESULT
--------------
it is zero
SQL> with t_minus as
2 (select empno from emp
3 minus
4 select deptno from dept
5 )
6 select case when count(*) = 0 then 'it is zero'
7 else 'it is not zero'
8 end result
9 from t_minus;
RESULT
--------------
it is not zero
SQL>
Related
I have a Query where there is number datatype column. In case of empty resultset O/P is blank. I want 0 in that case.
My query is
select nvl(infodata,0)
from table1
where group_id = 111
and appid in (select max(id)
from table1, table2
where status = 'A');
Now my inner query is returning null in that case. NVL seems to be not working on infodata column. Please help
Outcome of such a query is no rows selected.
For example (based on Scott's EMP and DEPT tables as I don't have yours, and you didn't post test case), this query returns nothing:
SQL> select e.deptno
2 from emp e
3 where e.ename = 'Littlefoot';
no rows selected
If it is used as a subquery, the result is equal to what you currently have:
SQL> select nvl(d.dname, 'x') result
2 from dept d
3 where d.deptno in (select e.deptno
4 from emp e
5 where e.ename = 'Littlefoot'
6 );
no rows selected
But, if you apply aggregation (see line #1), then you'd get what you wanted:
SQL> select nvl(max(d.dname), 'x') result
2 from dept d
3 where d.deptno in (select e.deptno
4 from emp e
5 where e.ename = 'Littlefoot'
6 );
RESULT
--------------
x
As I said: it works on my test case; might, or might not on yours. If you post sample data, we'd have something to work with.
I want to concat to the output based on condition. Here is my query:
select 'hey',
case id =1 then 'Mary' else 'Tom' end
from names;'
I want to print 'hey tom' or 'hey mary' based on id ... any help ??
It is concatenation you need; in Oracle, double pipe || represents that operator:
SQL> with names (id) as
2 (select 1 from dual union all
3 select 2 from dual union all
4 select 3 from dual
5 )
6 select id,
7 'hey ' || case when id = 1 then 'Mary'
8 else 'Tom'
9 end result
10 from names;
ID RESULT
---------- ----------
1 hey Mary
2 hey Tom
3 hey Tom
SQL>
You can run something like this query:
SELECT CONCAT('hey ', FIRST_NAME) from names where ID = '1';
Here's my SQL:
select
count(*)
from
sysdba.dw_cmap_arf_tmp
left join SYSDBA.TABLE1 rrc
on rrc.part_work_order = pwo
left join sysdba.TABLE2 R
on rrc.run_number = R.RUN_NUMBER
where
upper(run_type) like '%FEE%'
group by
pwo;
When there's nothing to group by, count returns --air--. It's null nor is it blank. I have modified the above SQL as the following to prove.
select
'>>' || count(*) || '<<' as blah
from
sysdba.dw_cmap_arf_tmp
left join SYSDBA.TABLE1 rrc
on rrc.part_work_order = pwo
left join sysdba.TABLE2 R
on rrc.run_number = R.RUN_NUMBER
where
upper(run_type) like '%ANNEAL%'
group by
pwo;
When I, however, write a statement above to perform an update, I got null. So tried coalesce, but got the same thing.
Does anyone know what I can do to replace --air-- with null or 0? Thanks!
P.S. I have did something research, but couldn't find anything...apologize in advance, if there's already a similar question out there.
Thanks!
This is what you currently have (based on Scott's EMP table): as there's no department 50, you get no rows selected (which is the air you're talking about, I presume).
SQL> with your_current_query as
2 (select count(*) cnt
3 from emp
4 where deptno = &deptno
5 group by job
6 )
7 select cnt
8 from your_current_query;
Enter value for deptno: 50
no rows selected
Just to show that it actually returns something if there are some data there:
SQL> /
Enter value for deptno: 30
CNT
----------
4
1
1
SQL>
OK; now, to do something with the situation where there are no rows selected, use union with a "dummy" row selected from the DUAL table:
SQL> with your_current_query as
2 (select count(*) cnt
3 from emp
4 where deptno = &deptno
5 group by job
6 )
7 select cnt
8 from your_current_query
9 -- add this: if YOUR_CURRENT_QUERY doesn't return anything, union it with
10 -- a select from dual
11 union all
12 select 0
13 from dual
14 where 0 = (select count(*) from your_current_query);
Enter value for deptno: 50
CNT
----------
0
SQL>
So: even though there are no employees in department 50, you got 0 as the result.
Again, to show what happens when there are some rows:
SQL> /
Enter value for deptno: 30
CNT
----------
4
1
1
SQL>
Finally, your query - rewritten - would look like this:
with your_current_query as
(select
count(*) cnt
from
sysdba.dw_cmap_arf_tmp
left join SYSDBA.TABLE1 rrc
on rrc.part_work_order = pwo
left join sysdba.TABLE2 R
on rrc.run_number = R.RUN_NUMBER
where
upper(run_type) like '%FEE%'
group by
pwo
)
select cnt from your_current_query
union all
select 0
from dual
where 0 = (select count(*) from your_Current_query);
See if it helps.
I'm trying to generate a Random String using PL/SQL with only 2 fixed words. It's this possible?
Is this what you're looking for?
SQL> with
2 -- two fixed words
3 test as
4 (select 'fixed words' col from dual),
5 -- split them to rows
6 inter as
7 (select level lvl, regexp_substr(col, '.', 1, level) let
8 from test
9 connect by level <= length(col)
10 )
11 -- aggregate them back, randomly
12 select listagg(let, '') within group (order by dbms_random.value(1, max_lvl)) result
13 from inter
14 join (select max(lvl) max_lvl from inter) on 1 = 1;
RESULT
--------------------------------------------------------------------------------
reiosdwxf d
SQL> /
RESULT
--------------------------------------------------------------------------------
fe ixoddrws
SQL> /
RESULT
--------------------------------------------------------------------------------
wdxeorsdfi
SQL>
My oracle version is 10.2.
It's very strange when a scalar subquery has an aggregate operation.
my table named t_test looked like this;
t_id t_name
1 1
2 1
3 2
4 2
5 3
6 3
query string looked like this;
select t1.t_id,
(select count(t_name)
from (select t2.t_name
from t_test t2
where t2.t_id=t1.t_id
group by t2.t_name)) a
from t_test t1
this query's result is,
t_id a
1 3
2 3
3 3
4 3
5 3
6 3
which is very weird,
take t1.t_id=1 for example,
select count(t_name)
from (select t2.t_name
from t_test t2
where t2.t_id=1
group by t2.t_name)
the result is 1,
somehow,the 'where' operator doesn't work,the result is exactly the same as I put my query like this:
select t1.t_id,
(select count(t_name)
from (select t2.t_name
from t_test t2
group by t2.t_name)) a
from t_test t1
why?
Can you post a cut-and-paste from SQL*Plus showing exactly what query you're running? The query you posted does not appear to be valid-- the alias t1 is not going to be valid in the subquery where you're referencing it. That makes me suspect that you're simplifying the problem to post here but you've accidentally left something important out.
SQL> ed
Wrote file afiedt.buf
1 with x as (
2 select 1 id, 1 name from dual union all
3 select 2,1 from dual union all
4 select 3,2 from dual union all
5 select 4,2 from dual union all
6 select 5,3 from dual union all
7 select 6,3 from dual
8 )
9 select t1.id
10 ,(select count(b.name)
11 from (select t2.name
12 from x t2
13 where t2.id = t1.id
14 group by t2.name) b) a
15* from x t1
SQL> /
where t2.id = t1.id
*
ERROR at line 13:
ORA-00904: "T1"."ID": invalid identifier
Presumably, it would be much more natural to write the query like this (assuming you really want to use a scalar subquery) where t1 is going to be a valid alias in the scalar subquery.
SQL> ed
Wrote file afiedt.buf
1 with x as (
2 select 1 id, 1 name from dual union all
3 select 2,1 from dual union all
4 select 3,2 from dual union all
5 select 4,2 from dual union all
6 select 5,3 from dual union all
7 select 6,3 from dual
8 )
9 select t1.id
10 ,(select count(t2.name)
11 from x t2
12 where t2.id = t1.id) cnt
13* from x t1
SQL> /
ID CNT
---------- ----------
1 1
2 1
3 1
4 1
5 1
6 1
6 rows selected.