I have database like this
(Example)
client_id
photo_type
date
1
license
13.10.2022
1
ident
12.10.2022
2
ident
15.10.2022
2
license
14.10.2022
3
license
15.10.2022
4
ident
16.10.2022
Where client has two types of photos, and i need to delete 1 type of photo(license or ident) by the date column(the oldest one). For example for client_id 1 i need to delete "ident", and for client 2 delete "license"
I need to use this process for a large amount of data
Please could you provide sollution for this process.
DELETE is such a costy operation especially for large data sets. Rather using a CreateTableAS statement might be preferred to quickly manage the same issue such as
CREATE TABLE t1 AS
SELECT client_id, photo_type, "date"
FROM (SELECT t.*, ROW_NUMBER() OVER (PARTITION BY client_id ORDER BY "date" DESC) AS rn
FROM t)
WHERE rn = 1
where the query only picks single row per each client_id even if ties occur for "date" values.
Demo
Here's one option: find rowids for rows you'd want to delete, and then ... well, delete them:
Sample data:
SQL> SELECT *
2 FROM test
3 ORDER BY client_id, datum;
CLIENT_ID PHOTO_T DATUM
---------- ------- ----------
1 ident 12.10.2022
1 license 13.10.2022
2 license 14.10.2022
2 ident 15.10.2022
3 license 15.10.2022
4 ident 16.10.2022
6 rows selected.
Delete:
SQL> DELETE FROM
2 test a
3 WHERE a.ROWID IN
4 (SELECT x.rid
5 FROM (SELECT ROWID rid,
6 b.client_id,
7 ROW_NUMBER ()
8 OVER (PARTITION BY b.client_id
9 ORDER BY b.datum DESC) rn
10 FROM test b) x
11 WHERE x.client_id = a.client_id
12 AND x.rn > 1);
2 rows deleted.
Result:
SQL> SELECT *
2 FROM test
3 ORDER BY client_id, datum;
CLIENT_ID PHOTO_T DATUM
---------- ------- ----------
1 license 13.10.2022
2 ident 15.10.2022
3 license 15.10.2022
4 ident 16.10.2022
SQL>
What about this?
DELETE FROM table a
WHERE EXISTS (
SELECT 1 FROM table b
WHERE b.client_id = a.client_id
AND b.date > a.date
)
Related
I have 2 tables - tab1 , tab2 with following data
tab1 data:
OID Label
1 MX1
1 MX2
1 MX3
2 MX4
2 MX5
tab2 data:
OID ID Label
1 5678
1 2347
1 9687
2 4567
2 3455
The join condition between these two tables is oid column.I need to create a process which will update Label column from tab1 to Label column of tab2.It doesn't matter which label gets assigned to which record of tab2 for a particular oid. The only check that needs to happen is that both the tables should have same number of records for an oid.The final outcome should be the following
tab2 data:
OID ID Label
1 5678 MX1
1 2347 MX2
1 9687 MX3
2 4567 MX4
2 3455 MX5
Again, it doesn't matter which label gets assigned to tab2 for a particular oid,but the same label cannot be repeated for a particular oid.What would be the best way to write a code for this requirement?
Here is a sql solution:
merge into tab2
using
(
select t2."id" as ide,t1."label" labela from
(select rownum n,"label","oid" from tab1 order by "oid")t1,
(select rownum n, a2.* from tab2 a2 order by "oid")t2
where t1.n=t2.n and
t1."oid"=t2."oid"
) tb4
on (tab2."id" = tb4.ide)
when matched then
update set tab2."label" = tb4.labela;
Result:
oid| id | label
-----------------
1 5678 mx1
1 2347 mx2
1 9687 mx3
2 4567 mx4
2 3455 mx5
Sample tables:
SQL> select * from tab1 order by oid, label;
OID LAB
---------- ---
1 mx1
1 mx2
1 mx3
2 mx4
2 mx5
SQL> select * from tab2 order by oid, id;
OID ID LAB
---------- ---------- ---
1 2347
1 5678
1 9687
2 3455
2 4567
SQL>
This is query that returns desired result:
SQL> with
2 t1 as (select oid, label, rowid rwid,
3 row_number() over (partition by oid order by label) rn
4 from tab1
5 ),
6 t2 as (select oid, id, rowid rwid,
7 row_number() over (partition by oid order by id) rn
8 from tab2
9 )
10 select b.oid, b.id, a.label
11 from t1 a join t2 b on a.oid = b.oid and a.rn = b.rn;
OID ID LAB
---------- ---------- ---
1 2347 mx1
1 5678 mx2
1 9687 mx3
2 3455 mx4
2 4567 mx5
SQL>
A few options I tried: correlated update won't work because of
ORA-01779: cannot modify a column which maps to a non key-preserved table
SQL> update (
2 with
3 t1 as (select oid, label, rowid rwid,
4 row_number() over (partition by oid order by label) rn
5 from tab1
6 ),
7 t2 as (select oid, id, rowid rwid, label,
8 row_number() over (partition by oid order by id) rn
9 from tab2
10 )
11 select b.oid, b.id, b.label b_label, a.label a_label
12 from t1 a join t2 b on a.oid = b.oid and a.rn = b.rn
13 )
14 set b_label = a_label;
set b_label = a_label
*
ERROR at line 14:
ORA-01779: cannot modify a column which maps to a non key-preserved table
SQL>
MERGE won't work because of
ORA-01732: data manipulation operation not legal on this view
SQL> merge into
2 (select oid, id, label, row_Number() over (partition by oid order by id ) rn from tab2) b
3 using (select oid, label, row_number() over (partition by oid order by label) rn from tab1) a
4 on (a.oid = b.oid and
5 a.rn = b.rn)
6 when matched then update set
7 b.label = a.label;
(select oid, id, label, row_Number() over (partition by oid order by id ) rn from tab2) b
*
ERROR at line 2:
ORA-01732: data manipulation operation not legal on this view
SQL>
Merge would accept a view (created with create view ...), but a view has to be updateable; this one can't be because it contains analytic function.
What's left is a PL/SQL procedure:
SQL> begin
2 for cur_r in (with
3 t1 as (select oid, label, rowid rwid,
4 row_number() over (partition by oid order by label) rn
5 from tab1
6 ),
7 t2 as (select oid, id, rowid rwid,
8 row_number() over (partition by oid order by id) rn
9 from tab2
10 )
11 select b.rwid, a.label
12 from t1 a join t2 b on a.oid = b.oid and a.rn = b.rn
13 )
14 loop
15 update tab2 b set
16 b.label = cur_r.label
17 where b.rowid = cur_r.rwid;
18 end loop;
19 end;
20 /
PL/SQL procedure successfully completed.
SQL> select * from tab2 order by oid, id;
OID ID LAB
---------- ---------- ---
1 2347 mx1
1 5678 mx2
1 9687 mx3
2 3455 mx4
2 4567 mx5
SQL>
Maybe someone has another idea; I'd like to see it & learn something new.
I'm new to PL SQL and have to write a function, which has customer_id as an input and has to output a product_name of the best selling product for that customer_id.
The schema looks like this:
I found a lot of simple examples where it includes two tables, but I can't seem to find one where you have to do multiple joins and use a function, while selecting only the best selling product.
I could paste a lot of very bad code here and how I tried to approach this, but this seems to be a bit over my head for current knowledge, since I've been learning PL SQL for less than 3 days now and got this task.
With some sample data (minimal column set):
SQL> select * from products order by product_id;
PRODUCT_ID PRODUCT_NAME
---------- ----------------
1 BMW
2 Audi
SQL> select * From order_items;
PRODUCT_ID CUSTOM QUANTITY UNIT_PRICE
---------- ------ ---------- ----------
1 Little 100 1
1 Little 200 2
2 Foot 300 3
If we check some totals:
SQL> select o.product_id,
2 o.customer_id,
3 sum(o.quantity * o.unit_price) total
4 from order_items o
5 group by o.product_id, o.customer_id;
PRODUCT_ID CUSTOM TOTAL
---------- ------ ----------
2 Little 400
1 Little 100
2 Foot 900
SQL>
It says that
for customer Little, product 2 was sold with total = 400 - that's our choice for Little
for customer Little, product 1 was sold with total = 100
for customer Foot, product 2 was sold with total = 900 - that's our choice for Foot
Query might then look like this:
temp CTE calculates totals per each customer
rank_them CTE ranks them in descending order per each customer; row_number so that you get only one product, even if there are ties
finally, select the one that ranks as the highest
SQL> with
2 temp as
3 (select o.product_id,
4 o.customer_id,
5 sum(o.quantity * o.unit_price) total
6 from order_items o
7 group by o.product_id, o.customer_id
8 ),
9 rank_them as
10 (select t.customer_id,
11 t.product_id,
12 row_number() over (partition by t.customer_id order by t.total desc) rn
13 from temp t
14 )
15 select * From rank_them;
CUSTOM PRODUCT_ID RN
------ ---------- ----------
Foot 2 1 --> for Foot, product 2 ranks as the highest
Little 2 1 --> for Little, product 1 ranks as the highest
Little 1 2
SQL>
Moved to a function:
SQL> create or replace function f_product (par_customer_id in order_items.customer_id%type)
2 return products.product_name%type
3 is
4 retval products.product_name%type;
5 begin
6 with
7 temp as
8 (select o.product_id,
9 o.customer_id,
10 sum(o.quantity * o.unit_price) total
11 from order_items o
12 group by o.product_id, o.customer_id
13 ),
14 rank_them as
15 (select t.customer_id,
16 t.product_id,
17 row_number() over (partition by t.customer_id order by t.total desc) rn
18 from temp t
19 )
20 select p.product_name
21 into retval
22 from rank_them r join products p on p.product_id = r.product_id
23 where r.customer_id = par_customer_id
24 and r.rn = 1;
25
26 return retval;
27 end;
28 /
Function created.
SQL>
Testing:
SQL> select f_product ('Little') result from dual;
RESULT
--------------------------------------------------------------------------------
Audi
SQL> select f_product ('Foot') result from dual;
RESULT
--------------------------------------------------------------------------------
Audi
SQL>
Now, you can improve it so that you'd care about no data found issue (when customer didn't buy anything), ties (but you'd then return a collection or a refcursor instead of a scalar value) etc.
[EDIT] I'm sorry, ORDERS table has to be included into the temp CTE; your data model is correct, you don't have to do anything about it - my query was wrong (small screen + late hours issue; not a real excuse, just saying).
So:
with
temp as
(select i.product_id,
o.customer_id,
sum(i.quantity * i.unit_price) total
from order_items i join orders o on o.order_id = i.order_id
group by i.product_id, o.customer_id
),
The rest of my code is - otherwise - unmodified.
I have a table which has data as:
id payor_name
---------------
1 AETNA
2 UMR
3 CIGNA
4 METLIFE
4 AETNAU
5 ktm
6 ktm
Id and payor_name are two columns.So,
My expected output is:
id payor_name
---------------
1 AETNA
2 UMR
3 CIGNA
4 METLIFE
4 AETNAU
6 ktm ...> I want to change the id of this row to be 6 from 5.
6 ktm
I want one to one mapping between id and payor_name.So,this is what I tried:
MERGE INTO offc.payor_collec A
USING (select id from offc.payor_collec where payor_name in(
select payor_name from offc.payor_collec group by payor_name having count(distinct id)>=2)) B
ON (A.id=B.id)
WHEN MATCHED THEN
UPDATE SET A.id=B.id
But when I compiled I got error as:
Error at line 1
ORA-38104: Columns referenced in the ON Clause cannot be updated: "A"."ID"
Id is number where as payor_name is varchar2.
How can I achieve this result?
MERGE works, but slightly different than your code.
SQL> select * from test;
ID PAYOR
---------- -----
1 aetna
2 umr
5 ktm
6 ktm
SQL> merge into test t
2 using (select max(t1.id) id,
3 t1.payor_name
4 from test t1
5 group by t1.payor_name
6 ) x
7 on (x.payor_name = t.payor_name)
8 when matched then update set
9 t.id = x.id;
4 rows merged.
SQL> select * from test;
ID PAYOR
---------- -----
1 aetna
2 umr
6 ktm
6 ktm
SQL>
Use a correlated subquery:
UPDATE PAYOR_COLLEC pc
SET pc.ID = (SELECT MAX(pc2.ID)
FROM PAYOR_COLLEC pc2
WHERE pc2.PAYOR_NAME = pc.PAYOR_NAME)
dbfiddle here
You can use a MERGE statement, as you tried and as Littlefoot has shown.
You can also use a correlated subquery as Bob Jarvis has shown, but that will be quite inefficient.
Many Oracle developers are unaware that you can also update through a join. Worse, there are many who say "there is no such thing in Oracle."
In your problem, you need to join your table to an aggregate query (picking just the max id for each payor_name) and the join is on the group by column in the aggregate. This already guarantees that the join column will be unique in the right-hand table; that is all Oracle needs to allow the update through join.
Here is a complete example, starting with the create table statement, then the update and then showing the table after the update. Note that I don't need any constraints (like primary key, not null, unique, etc.) or indexes on the base table. If they do exist, so much the better, but the solution works in the most general case.
create table t (id, payor_name) as
select 1, 'AETNA' from dual union all
select 2, 'UMR' from dual union all
select 3, 'CIGNA' from dual union all
select 4, 'METLIFE' from dual union all
select 4, 'AETNAU' from dual union all
select 5, 'ktm' from dual union all
select 6, 'ktm' from dual;
Table T created.
update
(
select id, payor_name, max_id
from t inner join
(select max(id) as max_id, payor_name from t group by payor_name)
using (payor_name)
)
set id = max_id where id != max_id
;
1 row updated.
select * from t;
ID PAYOR_NAME
----- ----------
1 AETNA
2 UMR
3 CIGNA
4 METLIFE
4 AETNAU
6 ktm
6 ktm
Notice the where clause at the end of the update statement, too. You don't want to update rows to their pre-existing value; that will still generate undo and redo data (although I understand that Oracle has changed that in more recent versions - it now doesn't generate undo and redo unless a row did indeed change). I assume ID is NOT NULL - otherwise you should rewrite the where clause as
where decode(id, max_id, 0) is null
or equivalent
I have a simple table with values (ID) in groups (GRP_ID).
create table tst as
select 1 grp_id, 1 id from dual union all
select 1 grp_id, 1 id from dual union all
select 1 grp_id, 2 id from dual union all
select 2 grp_id, 1 id from dual union all
select 2 grp_id, 2 id from dual union all
select 2 grp_id, 2 id from dual union all
select 3 grp_id, 3 id from dual;
It is straightforward to find a maximum value per group using analytical functions.
select grp_id, id,
max(id) over (partition by grp_id) max_grp
from tst
order by 1,2;
GRP_ID ID MAX_GRP
---------- ---------- ----------
1 1 2
1 1 2
1 2 2
2 1 2
2 2 2
2 2 2
3 3 3
But the goal is to find the maximum value excluding the value of the current row.
This is the expected result (column MAX_OTHER_ID):
GRP_ID ID MAX_GRP MAX_OTHER_ID
---------- ---------- ---------- ------------
1 1 2 2
1 1 2 2
1 2 2 1
2 1 2 2
2 2 2 2
2 2 2 2
3 3 3
Note that in the GRP_ID = 2 a tie on the MAX value exists, so the MAX_OTHER_ID remains the same.
I did manage this two step solution, but I'm wondering if there is a more straightforward and simple solution.
with max1 as (
select grp_id, id,
row_number() over (partition by grp_id order by id desc) rn
from tst
)
select GRP_ID, ID,
case when rn = 1 /* MAX row per group */ then
max(decode(rn,1,to_number(null),id)) over (partition by grp_id)
else
max(id) over (partition by grp_id)
end as max_other_id
from max1
order by 1,2
;
I wish the window functions supported multiple range specifications something like:
max(id) over (
partition by grp_id
order by id
range between unbounded preceding and 1 preceding
or range between 1 following and unbounded following
)
But unfortunately they don't.
As a workaround, you can avoid subqueries and CTEs using the function twice on the different ranges and call coalesce on that.
select grp_id,
id,
coalesce(
max(id) over (
partition by grp_id
order by id
range between 1 following and unbounded following
)
, max(id) over (
partition by grp_id
order by id
range between unbounded preceding and 1 preceding
)
) max_grp
from tst
order by 1,
2
Coalesce works out of the box because of the ordering clause as the result of the window function call will be either the max in the given window or a null value.
Demo - http://rextester.com/SDXVF13962
SELECT GRP_ID,ID, (SELECT Max(ID) FROM TEST A WHERE A.ROWID<>B.ROWID AND A.GRP_ID=B.GRP_ID) maX_ID FROM TEST B;
Got the expected result with Co-Related Query ! Hope this helps .
Please help me make an oracle stored procedure ; I have two tables
tblLead:
lead_id Name
1 x
2 y
3 z
tblTransaction:
Tran_id lead_id date status
1 1 04/20/2010 call Later
2 1 05/05/2010 confirmed
I want a result like
lead_id Name status
1 x confirmed
2 y not available !
3 z not available !
Use an outer join to the relevant rows of tblTransaction:
SQL> SELECT l.lead_id, l.NAME,
2 CASE
3 WHEN t.status IS NULL THEN
4 'N/A'
5 ELSE
6 t.status
7 END status
8 FROM tbllead l
9 LEFT JOIN (SELECT lead_id,
10 MAX(status) KEEP(DENSE_RANK FIRST
11 ORDER BY adate DESC) status
12 FROM tbltransaction
13 GROUP BY lead_id) t ON l.lead_id = t.lead_id;
LEAD_ID NAME STATUS
---------- ---- ----------
1 x confirmed
2 y N/A
3 z N/A
Alternatively you can use analytics:
SQL> SELECT lead_id, NAME, status
2 FROM (SELECT l.lead_id, l.NAME,
3 CASE
4 WHEN t.status IS NULL THEN
5 'N/A'
6 ELSE
7 t.status
8 END status,
9 row_number()
10 over(PARTITION BY l.lead_id ORDER BY t.adate DESC) rn
11 FROM tbllead l
12 LEFT JOIN tbltransaction t ON l.lead_id = t.lead_id)
13 WHERE rn = 1;
LEAD_ID NAME STATUS
---------- ---- ----------
1 x confirmed
2 y N/A
3 z N/A
It can be written in plain SQL as follows,
SELECT lead_id, name, NVL(status,'not available !')
FROM (
SELECT tblLead.lead_id, tblLead.name, tblTransaction.status,
rank ( ) OVER (PARTITION BY tblTransaction.lead_id ORDER BY tblTransaction.datee DESC, tblTransaction.tran_id DESC) rank
FROM tblLead
LEFT JOIN tblTransaction ON tblLead.lead_id = tblTransaction.lead_id
)
WHERE rank = 1
ORDER BY lead_id;
Or you may think of writing a view as follows,
CREATE VIEW trx_view AS
------
------;
Personally I think stored procedure is not necessary for scenarios like this.