I have a gauge chart that displays a value label and a percentage. it is based on a query that returns VALUE and MAX_VALUE. In some cases the query returns 0 as MAX_VALUE and then the chart displays a message 'Invalid data'. I believe this is happening because of division by zero. How to prevent this message from getting displayed and return 0 as both VALUE and MAX_VALUE and 0%?
SELECT NUM_FAILED VALUE, TOTAL_NUM MAX_VALUE
FROM
(
SELECT (
SELECT COUNT(*) FROM (select t1.name, t1.run_id
from Table1 t1
LEFT JOIN Table2 t2 ON t1.ID=t2.ID
WHERE t1.START_DATE > SYSDATE - 1
GROUP BY t1.name, t1.run_id)
) AS TOTAL_NUM,
(
SELECT COUNT(*) FROM (select name, run_id
from Table1 t1
LEFT JOIN Tabe2 t2 ON t1.ID=t2.ID
where t1.run_id IN (SELECT run_id FROM Table1 where err_code > 0)
AND t1.START_DATE > SYSDATE - 1
GROUP BY t1.name, t1.run_id)
) as NUM_FAILED
FROM dual)
Thank you for posting a query.
If you want to avoid 0 as a result, how about DECODE?
SELECT decode(NUM_FAILED, 0, 1E99, NUM_FAILED) VALUE,
decode(TOTAL_NUM , 0, 1E99, TOTAL_NUM ) MAX_VALUE
FROM (the rest of your query goes here)
You didn't say what's going on afterwards (i.e. what exactly causes division by zero - is it NUM_FAILED, or TOTAL_NUM)? The idea is: instead of dividing by zero, divide by a very large value (such as 1E99) and you'll get a very small number, for example:
SQL> select 24/1E99 from dual;
24/1E99
----------
2,4000E-98
SQL>
which is, practically, zero. See if you can do something with such an approach.
Related
I would like to query an Oracle DB table for the number of rows containing each distinct value in a CLOB column.
This returns all rows containing a value:
select * from mytable where dbms_lob.instr(mycol,'value') > 0;
Using DBMS_LOB, this returns the number of rows containing that value:
select count(*) from mytable where dbms_lob.instr(mycol,'value') > 0;
But is it possible to query for the number of times (rows in which) each distinct value appears?
Depending on what that column really contains, see whether TO_CHAR helps.
SQL> create table mytable (mycol clob);
Table created.
SQL> insert into mytable
2 select 'Query to count distinct values' from dual union all
3 select 'I have no idea which values are popular' from dual;
2 rows created.
SQL> select count(*), to_char(mycol) toc
2 from mytable
3 where dbms_lob.instr(mycol,'value') > 0
4 group by to_char(mycol);
COUNT(*) TOC
---------- ----------------------------------------
1 Query to count distinct values
1 I have no idea which values are popular
SQL>
If your CLOB values are more than 4000 bytes (and if not, why are they CLOBs?) then it's not perfect - collisions are possible, if unlikely - but you could hash the CLOB values.
If you want to count the number of distinct values:
select count(distinct dbms_crypto.hash(src=>mycol, typ=>2))
from mytable
where dbms_lob.instr(mycol,'value') > 0;
If you want to count how many times each distinct value appears:
select mycol, cnt
from (
select mycol,
count(*) over (partition by dbms_crypto.hash(src=>mycol, typ=>2)) as cnt,
row_number() over (partition by dbms_crypto.hash(src=>mycol, typ=>2) order by null) as rn
from mytable
where dbms_lob.instr(mycol,'value') > 0
)
where rn = 1;
Both are likely to be fairly expensive and slow with a lot of data.
(typ=>2 gives the numeric value for dbms_crypto.hash_md5, as you can't refer to the package constant in a SQL call, at least up to 12cR1...)
Rather more crudely, but possibly significantly quicker, you could base the count on the just the first 4000 characters - which may or may not be plausible for your actual data:
select count(distinct dbms_lob.substr(mycol, 4000, 1))
from mytable
where dbms_lob.instr(mycol,'value') > 0;
select dbms_lob.substr(mycol, 4000, 1), count(*)
from mytable
where dbms_lob.instr(mycol,'value') > 0
group by dbms_lob.substr(mycol, 4000, 1);
Standard Oracle functions do not support distinction of CLOB values. But, if you have access to DBMS_CRYPTO.HASH function, you can compare CLOB hashes instead, and thus, get the desired output:
select myCol, h.num from
myTable t join
(select min(rowid) rid, count(rowid) num
from myTable
where dbms_lob.instr(mycol,'value') > 0
group by DBMS_CRYPTO.HASH(myCol, 3)) h
on t.rowid = h.rid;
Also, note, that there's a very little possibility of hash collision. But if that's ok with you, you can use this approach.
I have a table student_info, it has column "status", status can be P (present), A (absent), S (ill), T ( transfer), L (left).
I am looking for expected output as below.
status count(*)
P 12
S 1
A 2
T 0
L 0
But output is coming like as below:
Status Count(*)
P 12
S 1
A 2
we need rows against status T and L as well with count zero though no record exist in DB.
#mkuligowski's approach is close, but you need an outer join between the CTE providing all of the possible status values, and then you need to count the entries that actually match:
-- CTE to generate all possible status values
with stored_statuses (status) as (
select 'A' from dual
union all select 'L' from dual
union all select 'P' from dual
union all select 'S' from dual
union all select 'T' from dual
)
select ss.status, count(si.status)
from stored_statuses ss
left join student_info si on si.status = ss.status
group by ss.status;
STATUS COUNT(SI.STATUS)
------ ----------------
P 12
A 2
T 0
S 1
L 0
The CTE acts as a dummy table holding the five statuses you want to count. That is then outer joined to your real table - the outer join means the rows from the CTE are still included even if there is no match - and then the rows that are matched in your table are counted. That allows the zero counts to be included.
You could also do this with a collection:
select ss.status, count(si.status)
from (
select column_value as status from table(sys.odcivarchar2list('A','L','P','S','T'))
) ss
left join student_info si on si.status = ss.status
group by ss.status;
It would be preferable to have a physical table which holds those values (and their descriptions); you could also then have a primary/foreign key relationship to enforce the allowed values in your existing table.
If all the status values actually appear in your table, but you have a filter which happens to exclude all rows for some of them, then you could get the list of all (used) values from the table itself instead of hard-coding it.
If your initial query was something like this, with a completely made-up filter:
select si.status, count(*)
from student_info si
where si.some_condition = 'true'
group by si.status;
then you could use a subquery to get all the distinct values from the unfiltered table, outer join from that to the same table, and apply the filter as part of the outer join condition:
select ss.status, count(si.status)
from (
select distinct status from student_info
) ss
left join student_info si on si.status = ss.status
and si.some_condition = 'true'
group by ss.status;
It can't stay as a where clause (at least here, where it's applying to the right-hand-side of the outer join) because that would override the outer join and effectively turn it back into an inner join.
You should store somewhere your statuses (pherhaps in another table). Otherwise, you list them using subquery:
with stored_statuses as (
select 'P' code, 'present' description from dual
union all
select 'A' code, 'absent' description from dual
union all
select 'S' code, 'ill' description from dual
union all
select 'T' code, 'transfer' description from dual
union all
select 'L' code, 'left' description from dual
)
select ss.code, count(*) from student_info si
left join stored_statuses ss on ss.code = si.status
group by ss.code
I have a scenario where I have to display a row 'n' number of times depending on the value in its quantity column.
Item Qty
abc 2
cde 1
Item Qty
abc 1
abc 1
cde 1
I am looking to convert the first table to the second.
I came across the site that I should be using the recursive WITH query.
My anchor member returns the original table.
SELECT ITEM, QTY
FROM lines
WHERE
JOB = TO_NUMBER ('1')
AND ITEM IN
(SELECT PART
FROM PICK
WHERE DELIVERY = '2')
My recursive member is as follows.
SELECT CTE.ITEM, (CTE.QTY - 1) QTY
FROM CTE
INNER JOIN
(SELECT ITEM, QTY
FROM LINES
WHERE JOB_ID = TO_NUMBER ('1')
AND ITEM IN
(SELECT PART
FROM PICK
WHERE DELIVERY = '2'
)) T
ON CTE.ITEM = T.ITEM
WHERE CTE.QTY > 1
My goal is to get all the parts and quantities first then and then for all parts with qty > 1 in the recursive step generate new rows to be added to the original result set and qty displayed in the new rows would be (original qty for that part - 1). The recursion would go on until qty becomes 1 for all the parts.
So this is what I had in the end.
WITH CTE (ITEM, QTY)
AS (
SELECT ITEM, QTY
FROM lines
WHERE
JOB = TO_NUMBER ('1')
AND ITEM IN
(SELECT PART
FROM PICK
WHERE DELIVERY = '2')
UNION ALL
SELECT CTE.ITEM, (CTE.QTY - 1) QTY
FROM CTE
INNER JOIN
(SELECT ITEM, QTY
FROM LINES
WHERE JOB_ID = TO_NUMBER ('1')
AND ITEM IN
(SELECT PART
FROM PICK
WHERE DELIVERY = '2'
)) T
ON CTE.ITEM = T.ITEM
WHERE CTE.QTY > 1)
SELECT ITEM, QTY
FROM CTE
ORDER BY 1, 2 DESC
I get the following error when I try the above
"ORA-32044: cycle detected while executing recursive WITH query"
How is it getting into a cycle? What did I miss in its working?
Also, Upon reading from another website If I used a "cycle clause". I was able to stop the cycle.
The clause I used was.
CYCLE
QUANTITY
SET
END TO '1'
DEFAULT '0'
If I used this before the select statement. I'm getting the desired output but I don't feel this is the right way of going about it. What exactly is the clause doing? What is the right way of using it?
Oracle Setup:
CREATE TABLE lines ( Item, Qty ) AS
SELECT 'abc', 2 FROM DUAL UNION ALL
SELECT 'cde', 1 FROM DUAL;
CREATE TABLE pick ( part, delivery ) AS
SELECT 'abc', 2 FROM DUAL UNION ALL
SELECT 'cde', 2 FROM DUAL;
Query 1: Using a hierarchical query:
SELECT Item,
COLUMN_VALUE AS qty
FROM lines l
CROSS JOIN
TABLE(
CAST(
MULTISET(
SELECT 1
FROM DUAL
CONNECT BY LEVEL <= l.Qty
)
AS SYS.ODCINUMBERLIST
)
) t
WHERE item IN ( SELECT part FROM pick WHERE delivery = 2 )
Query 2: Using a recursive sub-query factoring clause:
WITH rsqfc ( item, qty ) AS (
SELECT item, qty
FROM lines l
WHERE item IN ( SELECT part FROM pick WHERE delivery = 2 )
UNION ALL
SELECT item, qty - 1
FROM rsqfc
WHERE qty > 1
)
SELECT item, 1 AS qty
FROM rsqfc;
Output:
ITEM | QTY
:--- | --:
abc | 1
abc | 1
cde | 1
db<>fiddle here
I created a dummy database for learning purposes, and I purposefully created some duplicated records in one of the tables. In every case I want to flag one of the duplicated records as Latest='Y', and the other record as 'N', and for every single record the Latest flag would be 'Y'.
I tried to use PlSQL to go through all of my records, but when I try to use the previously calculated value (which would tell that its a duplicated record) it says that:
ORA-06550: line 20, column 17:
PLS-00201: identifier 'COUNTER' must be declared
Here is the statement I try to use:
DECLARE
CURSOR cur
IS
SELECT order_id, order_date, person_id,
amount, successfull_order, country_id, latest, ROWCOUNT AS COUNTER
FROM (SELECT order_id,
order_date,
person_id,
amount,
successfull_order,
country_id,
latest,
ROW_NUMBER () OVER (PARTITION BY order_id, order_date,
person_id, amount, successfull_order, country_id
ORDER BY order_id, order_date,
person_id, amount, successfull_order, country_id) ROWCOUNT
FROM orders) orders
FOR UPDATE OF orders.latest;
rec cur%ROWTYPE;
BEGIN
FOR rec IN cur
LOOP
IF MOD (COUNTER, 2) = 0
THEN
UPDATE orders
SET latest = 'N'
WHERE CURRENT OF cur;
ELSE
UPDATE orders
SET latest = 'Y'
WHERE CURRENT OF cur;
END IF;
END LOOP;
END;
I am new to PlSQL so I tried to modify the statements I found here:
http://www.adp-gmbh.ch/ora/plsql/cursors/for_update.html
What should I change in my statement, or should I use a different approach?
Thanks for your answers in advance!
Botond
Your refer the ROWNUM as COUNTER in your cursor.
While fetching, you should be accessing it from the cursor reference like MOD (rec.COUNTER, 2)
You need to declare the variable COUNTER and then you need to maintain (ie increment) it in your loop.
I suspect that you example is just for learning PL/SQL. However be aware that it's often much more performant to do things with a single SQL statement, as opposed to using cursor loops.
Your issue is that COUNTER is an attribute of the cursor record rec and not a PL/SQL variable. So:
IF MOD (COUNTER, 2) = 0
Should be:
IF MOD (rec.COUNTER, 2) = 0
However, you do not need to use PL/SQL or cursors, it can be done in a single MERGE statement:
Oracle Setup:
CREATE TABLE orders ( order_id, order_date, latest ) AS
SELECT 1, DATE '2017-01-01', CAST( NULL AS CHAR(1) ) FROM DUAL UNION ALL
SELECT 1, DATE '2017-01-02', NULL FROM DUAL UNION ALL
SELECT 1, DATE '2017-01-03', NULL FROM DUAL UNION ALL
SELECT 2, DATE '2017-01-04', NULL FROM DUAL UNION ALL
SELECT 2, DATE '2017-01-01', NULL FROM DUAL UNION ALL
SELECT 3, DATE '2017-01-06', NULL FROM DUAL;
Update Statement:
MERGE INTO orders dst
USING ( SELECT ROW_NUMBER() OVER ( PARTITION BY order_id
ORDER BY order_date DESC ) AS rn
FROM orders
) src
ON ( src.ROWID = dst.ROWID )
WHEN MATCHED THEN
UPDATE SET latest = CASE src.rn WHEN 1 THEN 'Y' ELSE 'N' END;
Output:
SELECT * FROM orders;
ORDER_ID ORDER_DATE LATEST
-------- ---------- ------
1 2017-01-01 N
1 2017-01-02 N
1 2017-01-03 Y
2 2017-01-04 Y
2 2017-01-01 N
3 2017-01-06 Y
I'm trying to create a query that will carry data forward to null rows. This is a fairly simple query with analytic functions LAG and LEAD
The query works when there is no partition by window and only one security_id. But, when I add that partition by and a second security_id, the last_value function fails. The bold rows do not appear.
Any ideas?
Thanks!
select t.*
,last_value(weight_pct ignore nulls) over
(partition by security_id order by n desc) value1 from (
select
datekey,portfolio_id,security_id,weight_pct
, n
from (
select to_date(first_date, 'yyyymmdd') -
to_date(datekey, 'yyyymmdd') day
,datekey
,portfolio_id
,security_id
,weight_pct
from ((select FIRST_VALUE(datekey) OVER(ORDER BY datekey desc ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) as first_date,
datekey,
portfolio_id,
security_id,
WEIGHT_PCT
from foo d
where security_id in (7,658900)
and portfolio_id = 2))) d
right outer join (select level as n
from dual
connect by level <= 95) l
on d.days = l.n) t
order by n, security_id, datekey desc
Because you have set an IGNORE NULLS On line 2?