Suppose I have the following tables
Target table
sales
ID ItemNum DiscAmt OrigAmt
1 123 20.00 NULL
2 456 30.00 NULL
3 123 20.00 NULL
Source Table
prices
ItemNum OrigAmt
123 25.00
456 35.00
I tried to update the OrigAmt in the Target Table using the OrigAmt in the Source Table using
UPDATE
( SELECT s.OrigAmt dests
,p.OrigAmt srcs
FROM sales s
LEFT JOIN prices p
ON s.ItemNum = p.ItemNum
) amnts
SET amnts.dests = amnts.srcs
;
but i get: ORA-01779: cannot modify a column which maps to a non key-preserved table
i also tried using the merge but i get: ORA-30926: unable to get a stable set of rows in the source tables
You cannot generally UPDATE the result of an arbitrary SELECT.
Single statement, assuming ItemNum is a primary key for prices:
UPDATE sales WHERE (SELECT count(price.ItemNum) FROM price
WHERE price.ItemNum = sales.ItemNum) > 0
SET OrigAmt =
(SELECT MAX(OrigAmt) FROM price
WHERE price.ItemNum = sales.ItemNum)
You might get away with omitting the WHERE and/or MAX.
Less convoluted: loop a cursor over
SELECT ItemNum, OrigAmt FROM price
performing a number of updates for each ItemNum from table prices:
UPDATE sales SET OrigAmt=? WHERE ItemNum=?
Related
I am looking for a possibly better approach to this.
I have created a temp table in Oracle 11.2 that I'm using to pre calculate values that I will need in other selects instead of always generating them again with each select.
create global temporary table temp_foo (
DT timestamp(6), --only the date part will be used in this example but for later things I will need the time
Something varchar2(100),
Customer varchar2(100),
MinDate timestamp(6),
MaxDate timestamp(6),
Filecount int,
Errorcount int,
AvgFilecount int,
constraint PK_foo primary key (DT, Customer)
) on commit preserve rows;
I then first insert some fixed values for everything except AvgFilecount. AvgFilecount should contain the average for the Filecount for the 3 previous records (going by the date in DT). It doesn’t matter that the result will be converted to an int, I don’t need the decimal places
DT | Customer | Filecount | AvgFilecount
2019-04-30 | x | 10 | avg(2+3+9)
2019-04-29 | x | 2 | based on values before this
2019-04-28 | x | 3 | based on values before this
2019-04-27 | x | 9 | based on values before this
I thought about using a normal UPDATE statement as this should be faster than looping through the values. I should mention that there are no gaps in the DT field but obviously there is a first one where I won‘t find any previous records. If I would loop through, I could easily calculate AvgFilecount with (the record before previous record/2 + previous record)/3 which I cannot with UPDATE as I cannot guarantee the order of how they are executed. So I‘m fine with just taking the last 3 records (going by DT) and calcuting it from there.
What I thought would be an easy update is giving me headaches. I‘m mostly doing SQL Server where I would just join the 3 other records but it seems is a bit different in Oracle. I have found https://stackoverflow.com/a/2446834/4040068 and wanted to use the second approach in the answer.
update
(select curr.DT, curr.temp_foo, curr.Filecount, curr.AvgFilecount as OLD, (coalesce(Minus1.Filecount, 0) + coalesce(Minus2.Filecount, 0) + coalesce(Minus3.Filecount, 0)) / 3 as NEW
from temp_foo curr
left join temp_foo Minus1 ON Minus1.Customer = curr.Customer and trunc(Minus1.DT) = trunc(curr.DT-1)
left join temp_foo Minus2 ON Minus2.Customer = curr.Customer and trunc(Minus2.DT) = trunc(curr.DT-2)
left join temp_foo Minus3 ON Minus3.Customer = curr.Customer and trunc(Minus3.DT) = curr.DT-3
order by 1, 2
)
set OLD = NEW;
Which gives me an
ORA-01779: cannot modify a column which maps to a non key-preserved
table
01779. 00000 - "cannot modify a column which maps to a non key-preserved table"
*Cause: An attempt was made to insert or update columns of a join view which
map to a non-key-preserved table.
*Action: Modify the underlying base tables directly.
I thought this should work as both join conditions are in the primary key and thus unique. I am currently implementing the first approach in the above mentioned answer but it is getting quite big and it feels like there should be a better solution to this.
Other things I thought about trying:
using a nested subselect (nested because Oracle doesn’t know top(n) and I need to sort the subselect) to select the previous 3 records ordered by DT and then he outer select with rownum <=3 and then I could just use AVG(). However, I was told subselect can be quite slow and joins are better in Oracle performance wise. Dunno if that is really the case, haven‘t done any testing
Edit: My insert right now looks like this. I am already aggregating the Filecount for a day as there can be multiple records per DT per Customer per Something.
insert into temp_foo (DT, Something, Customer, Filecount)
select dates.DT, tbl1.Something, tbl1.Customer, coalesce(sum(tbl3.Filecount),0)
from table(Function_Returning_Daterange(NULL, NULL)) dates
cross join
(SELECT Something,
Code,
Value
FROM Table2 tbl2
WHERE (Something = 'Value')) tbl1
left outer join Table3 tbl3
on tbl3.Customer = tbl1.Customer
and trunc(tbl3.MinDate) = trunc(dates.DT)
group by dates.DT, tbl1.Something, tbl1.Customer;
You could use an analytic average with a window clause:
select dt, customer, filecount,
avg(filecount) over (partition by customer order by dt
rows between 3 preceding and 1 preceding) as avgfilecount
from tmp_foo
order by dt desc;
DT CUSTOMER FILECOUNT AVGFILECOUNT
---------- -------- ---------- ------------
2019-04-30 x 10 4.66666667
2019-04-29 x 2 6
2019-04-28 x 3 9
2019-04-27 x 9
and then do the update part with a merge statement:
merge into tmp_foo t
using (
select dt, customer,
avg(filecount) over (partition by customer order by dt
rows between 3 preceding and 1 preceding) as avgfilecount
from tmp_foo
) s
on (s.dt = t.dt and s.customer = t.customer)
when matched then update set t.avgfilecount = s.avgfilecount;
4 rows merged.
select dt, customer, filecount, avgfilecount
from tmp_foo
order by dt desc;
DT CUSTOMER FILECOUNT AVGFILECOUNT
---------- -------- ---------- ------------
2019-04-30 x 10 4.66666667
2019-04-29 x 2 6
2019-04-28 x 3 9
2019-04-27 x 9
You haven't shown your original insert statement; it might be possible to add the analytic calculation to that, and avoid the separate update step.
Also, if you want the first two date values to be calculated as if the 'missing' extra days before them had zero counts, you could use sum and division instead of avg:
select dt, customer, filecount,
sum(filecount) over (partition by customer order by dt
rows between 3 preceding and 1 preceding)/3 as avgfilecount
from tmp_foo
order by dt desc;
DT CUSTOMER FILECOUNT AVGFILECOUNT
---------- -------- ---------- ------------
2019-04-30 x 10 4.66666667
2019-04-29 x 2 4
2019-04-28 x 3 3
2019-04-27 x 9
It depends what you expect those last calculated values to be.
I have two tables affiliation and customer, in that i have data like this
aff_id From_cus_id
------ -----------
1 10
2 20
3 30
4 40
5 50
cust_id cust_aff_id
------- -------
10
20
30
40
50
i need to update data for cust_aff_id column from affiliation table which is aff_id like below
cust_id cust_aff_id
------- -------
10 1
20 2
30 3
40 4
50 5
could u please give reply if anyone knows......
Oracle doesn't have an UPDATE with join syntax, but you can use a subquery instead:
UPDATE customer
SET customer.cust_aff_id =
(SELECT aff_id FROM affiliation WHERE From_cus_id = customer.cust_id)
merge into customer t2
using affiliation t1 on (t1.From_cus_id =t2.cust_id )
WHEN MATCHED THEN
update set t2.cust_aff_id = t1.aff_id
;
Here is an update with join syntax. This, quite reasonably, works only if from_cus_id is primary key in the first table and cust_id is foreign key in the second table, referencing the first table. Without these conditions, the requirement doesn't make much sense in the first place anyway... but Oracle requires that these constraints be stated explicitly in the tables. This is also reasonable on Oracle's part IMO.
update
( select t1.aff_id, t2.cust_aff_id
from affiliation t1 join customer t2 on t2.cust_id = t1.from_cus_id) j
set j.cust_aff_id = j.aff_id;
First, I execute the following SQL statements.
drop table names;
drop table ages;
create table names (id number, name varchar2(20));
insert into names values (1, 'Harry');
insert into names values (2, 'Sally');
insert into names values (3, 'Barry');
create table ages (id number, age number);
insert into ages values (1, 25);
insert into ages values (2, 30);
insert into ages values (3, 35);
select * from names;
select * from ages;
As a result, the following tables are created.
ID NAME
---------- ----------
1 Harry
2 Sally
3 Barry
ID AGE
---------- ----------
1 25
2 30
3 35
Now, I want to update increment the age of Sally by 1, i.e. set it to 31. The following query works fine.
update ages set age = age + 1 where id = (select id from names where name = 'Sally');
select * from ages;
The table now looks like this.
ID AGE
---------- ----------
1 25
2 31
3 35
I want to know if there is a way it can be done by joins. For example, I tried the following queries but they fail.
SQL> update ages set age = age + 1 from ages, names where ages.id = names.id and names.name = 'Sally';
update ages set age = age + 1 from ages, names where ages.id = names.id and names.name = 'Sally'
*
ERROR at line 1:
ORA-00933: SQL command not properly ended
SQL> update ages set age = age + 1 from names join ages on ages.id = names.id where names.name = 'Sally';
update ages set age = age + 1 from names join ages on ages.id = names.id where names.name = 'Sally'
*
ERROR at line 1:
ORA-00933: SQL command not properly ended
The syntax of the UPDATE statement is:
http://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_10007.htm
where dml_table_expression_clause is:
Please pay attention on ( subquery ) part of the above syntax.
The subquery is a feature that allows to perform an update of joins.
In the most simplest form it can be:
UPDATE (
subquery-with-a-join
)
SET cola=colb
Before update a join, you must know restrictions listed here:
https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_8004.htm
The view must not contain any of the following constructs:
A set operator
A DISTINCT operator
An aggregate or analytic function
A GROUP BY, ORDER BY, MODEL, CONNECT BY, or START WITH clause
A collection expression in a SELECT list
A subquery in a SELECT list
A subquery designated WITH READ ONLY
Joins, with some exceptions, as documented in Oracle Database Administrator's Guide
and also common rules related to updatable views - here (section: Updating a Join View):
http://docs.oracle.com/cd/B19306_01/server.102/b14231/views.htm#sthref3055
All updatable columns of a join view must map to columns of a
key-preserved table. See "Key-Preserved Tables" for a discussion of
key-preserved tables. If the view is defined with the WITH CHECK
OPTION clause, then all join columns and all columns of repeated
tables are not updatable.
We can first create a subquery with a join:
SELECT age
FROM ages a
JOIN names m ON a.id = m.id
WHERE m.name = 'Sally'
This query simply returns the following result:
AGE
----------
30
and now we can try to update our query:
UPDATE (
SELECT age
FROM ages a
JOIN names m ON a.id = m.id
WHERE m.name = 'Sally'
)
SET age = age + 1;
but we get an error:
SQL Error: ORA-01779:cannot modify a column which maps to a non key-preserved table
This error means, that one of the above restriction is not meet (key-preserved table).
However if we add primary keys to our tables:
alter table names add primary key( id );
alter table ages add primary key( id );
then now the update works without any error and a final outcome is:
select * from ages;
ID AGE
---------- ----------
1 25
2 31
3 35
I have source table and a target table I want to do merge such that there should always be insert in the target table. For each record updated there should ne a flag updated to 'Y' and when this in something is changed then record flag value should be chnaged to 'N' and a new row of that record is inserted in target such that the information of record that is updated should be reflected. Basically I want to implement SCD type2 . My input data is-
student_id name city state mobile
1 suraj bhopal m.p. 9874561230
2 ravi pune mh 9874563210
3 amit patna bihar 9632587410
4 rao banglore kr 9236547890
5 neel chennai tn 8301456987
and when my input chnages-
student_id name city state mobile
1 suraj indore m.p. 9874561230
And my output should be like-
surr_key student_id name city state mobile insert_Date end_date Flag
1 1 suraj bhopal m.p.9874561230 31/06/2015 1/09/2015 N
2 1 suraj indore m.p.9874561230 2/09/2015 31/12/9999 Y
Can anyone help me how can I do that?
You can do this with the use of trigger ,you can create before insert trigger on your target table which will update flag column of your source table.
Or you can have after update trigger on source table which will insert record in your target table.
Hope this helps
Regards,
So this should be the outline of your procedure steps. I used different columns in source and target for simplification.
Source (tu_student) - STUDENT_ID, NAME, CITY
Target (tu_student_tgt)- SKEY, STUDENT_ID, NAME, CITY, INSERT_DATE, END_DATE, IS_ACTIVE
The basic idea here is
Find the new records from source which are missing in target and Insert it. Set start_date as sysdate, end_date as 9999 and IsActive to 1.
Find the records which are updated (like your Bhopal -> Indore case). So we have to do 2 operations in target for it
Update the record in target and set end date as sysdate and IsActive to 0.
Insert this record in target which has new values. Set start_date as sysdate, end_date as 9999 and IsActive = 1.
-- Create a new oracle sequence (test_utsav_seq in this example)
---Step 1 - Find new inserts (records present in source but not in target
insert into tu_student_tgt
(
select
test_utsav_seq.nextval as skey,
s.student_id as student_id,
s.name as name,
s.city as city,
sysdate as insert_date,
'31-DEC-9999' as end_date,
1 as Flag
from tu_student s
left outer join
tu_student_tgt t
on s.student_id=t.student_id
where t.student_id is null)
----Step 2 - Find skey which needs to be updated due to data chage from source and target. So get the active records from target and compare with source data. If mismatch found, we need to
-- a update this recods in target and mark it as Inactive.
-- b Insert a new record for same student_id with new data and mark it Active.
-- part 2a - find updates.
--these records need update. Save these skey and use it one by one while updating.
select t.skey
from tu_student s inner join
tu_student_tgt t
on s.student_id=t.student_id
where t.Flag = 1 and
(s.name!=t.name or
s.city!=t.city)
--2 b ) FInd the ids which needs to be inserted as they changed in source from target. Now as above records are marked inactive,
select s.student_id
from tu_student s inner join
tu_student_tgt t
on s.student_id=t.student_id
where t.Flag = 1 and
(s.name!=t.name or
s.city!=t.city)
---2a - Implement update
-- Now use skey from 2a in a loop and run update statements like below. Replace t.key = with the keys which needs to be updated.
update tu_student_tgt t
set t.student_id = (select s.student_id from tu_student s,tu_student_tgt t where s.student_id=t.student_id and t.key= -- id from 2a step . )
, t.name=(select s.name from tu_student s,tu_student_tgt t where s.student_id=t.student_id and t.key= --id from 2a step. )
, end_date = sysdate
, is_active = 0
where t.skey = -- id from 2a step
---2b Implement Insert use student_id found in 2a
--Insert these student id like step 1
insert into tu_student_tgt
(
select
test_utsav_seq.nextval as skey,
s.student_id as student_id,
s.name as name,
s.city as city,
sysdate as insert_date,
'31-DEC-9999' as end_date,
1 as Flag
from tu_student s
where s.student_id = -- ID from 2b step - Repeat for other ids
I cannot give you a simple example of SCD-2. If you understand SCD-2, you should understand this implementation.
Let's say I have table data similar to the following:
123456 John Doe 1 Green 2001
234567 Jane Doe 1 Yellow 2001
234567 Jane Doe 2 Red 2001
345678 Jim Doe 1 Red 2001
What I am attempting to do is only isolate the records for Jane Doe based upon the fact that she has more than one row in this table. (More that one sequence number)
I cannot isolate based upon ID, names, colors, years, etc...
The number 1 in the sequence tells me that is the first record and I need to be able to display that record, as well as the number 2 record -- The change record.
If the table is called users, and the fields called ID, fname, lname, seq_no, color, date. How would I write the code to select only records that have more than one row in this table? For Example:
I want the query to display this only based upon the existence of the multiple rows:
234567 Jane Doe 1 Yellow 2001
234567 Jane Doe 2 Red 2001
In PL/SQL
First, to find the IDs for records with multiple rows you would use:
SELECT ID FROM table GROUP BY ID HAVING COUNT(*) > 1
So you could get all the records for all those people with
SELECT * FROM table WHERE ID IN (SELECT ID FROM table GROUP BY ID HAVING COUNT(*) > 1)
If you know that the second sequence ID will always be "2" and that the "2" record will never be deleted, you might find something like:
SELECT * FROM table WHERE ID IN (SELECT ID FROM table WHERE SequenceID = 2)
to be faster, but you better be sure the requirements are guaranteed to be met in your database (and you would want a compound index on (SequenceID, ID)).
Try something like the following. It's a single tablescan, as opposed to 2 like the others.
SELECT * FROM (
SELECT t1.*, COUNT(name) OVER (PARTITION BY name) mycount FROM TABLE t1
)
WHERE mycount >1;
INNER JOIN
JOIN:
SELECT u1.ID, u1.fname, u1.lname, u1.seq_no, u1.color, u1.date
FROM users u1 JOIN users u2 ON (u1.ID = u2.ID and u2.seq_no = 2)
WHERE:
SELECT u1.ID, u1.fname, u1.lname, u1.seq_no, u1.color, u1.date
FROM users u1, thetable u2
WHERE
u1.ID = u2.ID AND
u2.seq_no = 2
Check out the HAVING clause for a summary query. You can specify stuff like
HAVING COUNT(*) >= 2
and so forth.