I want to migrate the data from SAP HANA to Oracle. But I have implemented some views using STRING_AGG in SAP HANA. Can we use LISTAGG for those implemented views in SAP HANA so that migration process will be easy. If possible please give an example. If not require advice.
I have used STRING_AGG in SAP HANA which made it is easier to summarize the data using ','. But I later found out that STRING_AGG is not available in Oracle. So I want to choose the equivalent of STRING_AGG for Oracle. Which is LISTAGG. I tried implementing LISTAGG in SAP HANA but it is saying
Output: invalid name of function or procedure: LISTAGG:
Example:
LISTAGG(CASE WHEN v1.OFFICE_ID in(4,5,6,7,8) THEN v1.ITEM_PDT_ID WHEN v1.office_id IS NULL THEN v1.ITEM_PDT_ID ELSE 0 END,', ') AS "ITEM_PDT_ID"
Which Oracle database version do you use? LISTAGG was introduced in (I believe) 11gR2 so - if you're using lower version than that, it (obviously) won't work.
SQL> SELECT LISTAGG (e.ename, ', ') WITHIN GROUP (ORDER BY e.ename) employees
2 FROM emp e
3 WHERE e.deptno = 10;
EMPLOYEES
--------------------------------------------------------------------------------
CLARK, KING, MILLER
SQL>
If you search the Internet, you might find another function - WM_CONCAT. It is undocumented so you shouldn't use it; besides, Oracle removed it from Oracle 12c (and newer versions), but works in lower versions (I ran this code in 11g):
SQL> SELECT wm_concat (e.ename) employees
2 FROM emp e
3 WHERE e.deptno = 10;
EMPLOYEES
--------------------------------------------------------------------------------
CLARK,KING,MILLER
SQL>
What you might do, is to use XMLAGG instead:
SQL> SELECT RTRIM (
2 XMLAGG (XMLELEMENT (e, e.ename || ', ') ORDER BY e.ename).EXTRACT (
3 '//text()'),
4 ', ') employees
5 FROM emp e
6 WHERE e.deptno = 10;
EMPLOYEES
--------------------------------------------------------------------------------
CLARK, KING, MILLER
SQL>
Related
I work primarily with SAS and Oracle and am still new to DB2. Im faced with needing a hierarchical query to separate a clob into chunks that can be pulled into sas. SAS has a limit of 32K for character variables so I cant just pull the dataset in normally.
I found an old stackoverflow question about the best way to pull a clob into a sas data set but it is written in Oracle.
Import blob through SAS from ORACLE DB
Since I am new to DB2 and the syntax for this type of join seems very different I was hoping to find someone that could help convert it and explain the syntax. I find the Oracle syntax to be much easier to understand. I'm not sure in DB2 if you would use a CTE recursion like this https://www.ibm.com/support/knowledgecenter/en/SSEPEK_10.0.0/apsg/src/tpc/db2z_xmprecursivecte.html or if you would use hierarchical queries like this https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_71/sqlp/rbafyrecursivequeries.htm
Here is the Oracle query.
SELECT
id
, level as chunk_id
, regexp_substr(clob_value, '.{1,32767}', 1, level, 'n') as clob_chunk
FROM (
SELECT id, clob_value
FROM schema.table
WHERE id = 1
)
CONNECT BY LEVEL <= regexp_count(clob_value, '.{1,32767}',1,'n')
order by id, chunk_id;
The table has two fields the id and the clob_value and would look like this.
ID CLOB_VALUE
1 really large clob
2 medium clob
3 another large clob
The thought is I would want this result. I would only ever be doing this one row at a time where id= which ever row I am processing.
ID CHUNK_ID CLOB
1 1 clob_chunk1of3
1 2 clob_chunk2of3
1 3 clob_chunk3of3
Thanks for any time spent reading and helping.
Here is a solution that should work in DB2 with few changes (but please be advised that I don't know DB2 at all; I am just using Oracle features that are in the SQL Standard, so they should be implemented identically - or almost so - in DB2).
Below I create a table with your sample data; then I show how to chunk it into substrings of length at most 8 characters. Although the strings are short, I defined the column as CLOB and I am using CLOB tools; this should work on much larger CLOBs.
You can make both the chunk size and the id into bind parameters, if needed. In my demo below I hardcoded the chunk size and I show the result for all IDs in the table. In case the CLOB is NULL, I do return one chunk (which is NULL, of course).
Note that touching CLOBs in a query is very expensive; so most of the work is done without touching the CLOBs. I only work on them as little as possible.
PREP WORK
drop table tbl purge; -- If needed
create table tbl (id number, clob_value clob);
insert into tbl (id, clob_value)
select 1, 'really large clob' from dual union all
select 2, 'medium clob' from dual union all
select 3, 'another large clob' from dual union all
select 4, null from dual -- added to check handling
;
commit;
QUERY
with
prep(id, len) as (
select id, dbms_lob.getlength(clob_value)
from tbl
)
, rec(id, len, ord, pos) as (
select id, len, 1, 1
from prep
union all
select id, len, ord + 1, pos + 8
from rec
where len >= pos + 8
)
select id, ord, dbms_lob.substr(clob_value, 8, pos)
from tbl inner join rec using (id)
order by id, ord
;
ID ORD CHUNK
---- ---- --------
1 1 really l
1 2 arge clo
1 3 b
2 1 medium c
2 2 lob
3 1 another
3 2 large cl
3 3 ob
4 1
Another option is to enable the Oracle compatibility in Db2 and just issue the hierarchical query.
This GitHub repository has background information on SQL recursion in DB2, including the Oracle-style syntax and a side by side example (both work against the Db2 sample database):
-- both queries are against the SAMPLE database
-- and should return the same result
SELECT LEVEL, CAST(SPACE((LEVEL - 1) * 4) || '/' || DEPTNAME
AS VARCHAR(40)) AS DEPTNAME
FROM DEPARTMENT
START WITH DEPTNO = 'A00'
CONNECT BY NOCYCLE PRIOR DEPTNO = ADMRDEPT;
WITH tdep(level, deptname, deptno) as (
SELECT 1, CAST( DEPTNAME AS VARCHAR(40)) AS DEPTNAME, deptno
FROM department
WHERE DEPTNO = 'A00'
UNION ALL
SELECT t.LEVEL+1, CAST(SPACE(t.LEVEL * 4) || '/' || d.DEPTNAME
AS VARCHAR(40)) AS DEPTNAME, d.deptno
FROM DEPARTMENT d, tdep t
WHERE d.admrdept=t.deptno and d.deptno<>'A00')
SELECT level, deptname
FROM tdep;
I have a procedure that throws the error "ORA-01427: single-row subquery returns more than one row". When I use the statemt as a simple SELECT I get 1 row per ID.
I researched the ORA-01427, however I couldn't really apply the answers to my error, since from what I understand I don't have a subquery.
CREATE OR REPLACE PROCEDURE CALC_SLOPE (TBL_NAME IN VARCHAR2) AS
BEGIN
EXECUTE IMMEDIATE 'ALTER TABLE '||TBL_NAME||' ADD (SLOPE_MEDIAN NUMBER(2,2),
SLOPE_75 NUMBER(2,2),
SLOPE_90 NUMBER(2,2))';
EXECUTE IMMEDIATE 'UPDATE '||TBL_NAME||' a1 SET(SLOPE_MEDIAN, SLOPE_75, SLOPE_90)
=(
SELECT ROUND(MEDIAN(b.SLOPE),2) AS SLOPE_MEDIAN,
ROUND(PERCENTILE_CONT(0.75) WITHIN GROUP (ORDER BY b.slope DESC),2) AS SLOPE_75,
ROUND(PERCENTILE_CONT(0.9) WITHIN GROUP (ORDER BY b.slope DESC),2) AS SLOPE_90
FROM '||TBL_NAME||' a2,
bbx_slope b
WHERE SDO_CONTAINS(a2.GEOMETRY, b.POINT) = ''TRUE''
GROUP BY a2.ID
)';
END CALC_SLOPE;
Where lies the reason for the error and how can it be fixed?
I am working on WINDOWS 10 on ORACLE 12c Enterprise Edition.
I think you wanted a correlated update
..
FROM '
|| tbl_name || ' a2 JOIN bbx_slope b
ON SDO_CONTAINS(a2.GEOMETRY, b.POINT) = ''TRUE''
WHERE a2.ID = a1.id --This one
GROUP BY a2.ID
..
Right now You trying to update single row:
SET(SLOPE_MEDIAN, SLOPE_75, SLOPE_90)
with your select result. If your SELECT returns 50 rows, this 50 rows ORACLE tries to put into this single row.
Your missing in WHERE clause some conditions on ID column
Here I have two data bases, DB1 and DB2. From DB2 procedure I want to call a function of DB1 like below
OPEN cur FOR
SELECT
TO_CHAR(TRANSACTION_DATE,'DD MM YYYY') as DATE_UTC,
TO_CHAR(TRANSACTION_DATE,'HH24:MI:SS') as TIME_UTC,
IP_ADDRESS,
(TRANSACTION_DATE + (UTC_TIMESTAMP() - SYSTIMESTAMP)) as Local_Time,
ID,
(select DB1.GET_NAME(12) from dual) as TEST_NAME;
When I call it from Oracle SQL worksheet, it is working; but when we call it in a cursor, it is not working.
I tried below both ways in that returning cursor:
(select DB1.GET_NAME(12) from dual) as TEST_NAME;
(DB1.GET_NAME(12)) as TEST_NAME;
Any one please help to resolve this issue.
There are plenty of stored procedure on 10g platform . ( Almost 500 SPs)
Each SP might have loop, fetch and etc.
I'd like to ask you if there is a cool method to control all the SPs which are currently running on 10g, and guarantee that it works on 11 g.
I have a development server 1 which is 10 g and the other development server is 11 g.
I can use both of them to testify the propose above.
For instance I know that on 10 g if you use loop, and during the loop the update statements do not affect the loop data but 11g.
There might be more cases that I have to consider. Please tell me if you have any brillant idea , otherwise I will check them up one by one manually and it is a lot of time and human control might be weak sometimes.
important note: It is said that if you select some data from a table or tables, and if you use it in a loop, then during de loop, if you update and commit between loop case, it affects the selected data in cursor.(#11g) But this did not happen #10g version. Please correct me if you heard something like that.
The Example Case;
CREATE TABLE vty_musteri(
musterino NUMBER NOT NULL,
subeadi VARCHAR2(61),
kayitzamani VARCHAR2(20)
);
INSERT INTO vty_musteri (musterino, subeadi, kayitzamani )
VALUES (12345, 'AMSTERDAM', '05/30/2012 15:11:13');
COMMIT;
CREATE UNIQUE INDEX vty_musteri_idx ON vty_musteri (musterino);
SELECT * FROM vty_musteri;
CREATE OR REPLACE PROCEDURE krd_upd_silseomusteri_sp(RC1 in out SYS_REFCURSOR) AS
v_musterino NUMBER := 12345;
BEGIN
OPEN RC1 FOR
SELECT m.musterino, m.subeadi, m.kayitzamani
FROM vty_musteri m
WHERE m.musterino = v_musterino;
update vty_musteri
set subeadi = 'PORTO',
kayitzamani = (SELECT TO_CHAR(SYSDATE, 'MM/DD/YYYY HH24:MI:SS')
FROM dual)
where musterino = v_musterino;
COMMIT;
After all run this test on PLSQL:
DECLARE
--test
vRecTip SYS_REFCURSOR;
TYPE vRecTipK IS RECORD(
musterino NUMBER,
subeadi VARCHAR2(61),
kayitzamani VARCHAR2(20)
);
v_SeoTip vRecTipK;
BEGIN
krd_upd_silseomusteri_sp(rc1 => vRecTip);
IF vRecTip%ISOPEN THEN
LOOP
FETCH vRecTip
INTO v_SeoTip;
EXIT WHEN vRecTip%NOTFOUND;
dbms_output.put_line('The Value : ' || v_SeoTip.musterino || ' - ' || v_SeoTip.subeadi || ' - ' || v_SeoTip.kayitzamani);
END LOOP;
END IF;
COMMIT;
END;
END;
If you run this on 10g you will see AMSTERDAM, but on 11G, it is PORTO.
To fix it; I put a hint in the sp like the following:
SELECT /*+ full(m)*/ m.musterino, m.subeadi, m.kayitzamani
Isn't it weird? any alternative sugesstion to get AMSTERDAM ?
One thing we stumbled upon during a migration were queries that weren't supposed to work on 10.x (but did anyway) did no longer work on 11.x
This happens if you have ambigous column references in your query.
Something like this:
SELECT name,
f.some_col,
b.other_col
FROM foo f,
JOIN bar b ON f.id = b.fid
If the column name exists in both tables, 10.x would run the statement - which was a bug.
This bug (BugID: 6760937) was fixed and makes the statement (rightfully) fail in 11.x
Basic PLSQL structures should work exactly the same. Some pitfalls are listed here:
http://www.help2ora.com/index.php/2011/08/04/be-careful-when-migrating-difference-between-oracle-10g-and-11g/
To fix it; I put a hint in the sp like the following:
SELECT /+ full(m)/ m.musterino, m.subeadi, m.kayitzamani
Recently I have done migration to Oracle 11g. Faced few unprecedented issues. I have written a blog post on this. Have a look http://learncodewrite.blogspot.in/2017/04/migrating-to-oracle-11g-from-oracle-10g.html?m=1.
We just converted our sql server stored procedures to oracle procedures. Sql Server SP's were highly dependent on session tables (INSERT INTO #table1...) these tables got converted as global temporary tables in oracle. We ended up with aroun 500 GTT's for our 400 SP's
Now we are finding out that working with GTT's in oracle is considered a last option because of performance and other issues.
what other alternatives are there? Collections? Cursors?
Our typical use of GTT's is like so:
Insert into GTT
INSERT INTO some_gtt_1
(column_a,
column_b,
column_c)
(SELECT someA,
someB,
someC
FROM TABLE_A
WHERE condition_1 = 'YN756'
AND type_cd = 'P'
AND TO_NUMBER(TO_CHAR(m_date, 'MM')) = '12'
AND (lname LIKE (v_LnameUpper || '%') OR
lname LIKE (v_searchLnameLower || '%'))
AND (e_flag = 'Y' OR
it_flag = 'Y' OR
fit_flag = 'Y'));
Update the GTT
UPDATE some_gtt_1 a
SET column_a = (SELECT b.data_a FROM some_table_b b
WHERE a.column_b = b.data_b AND a.column_c = 'C')
WHERE column_a IS NULL OR column_a = ' ';
and later on get the data out of the GTT. These are just sample queries, in actuality the queries are really complext with lot of joins and subqueries.
I have a three part question:
Can someone show how to transform
the above sample queries to
collections and/or cursors?
Since
with GTT's you can work natively
with SQL...why go away from the
GTTs? are they really that bad.
What should be the guidelines on
When to use and When to avoid GTT's
Let's answer the second question first:
"why go away from the GTTs? are they
really that bad."
A couple of days ago I was knocking up a proof of concept which loaded a largish XML file (~18MB) into an XMLType. Because I didn't want to store the XMLType permanently I tried loading it into a PL/SQL variable (session memory) and a temporary table. Loading it into a temporary table took five times as long as loading it into an XMLType variable (5 seconds compared to 1 second). The difference is because temporary tables are not memory structures: they are written to disk (specifically your nominated temporary tablespace).
If you want to cache a lot of data then storing it in memory will stress the PGA, which is not good if you have lots of sessions. So it's a trade-off between RAM and time.
To the first question:
"Can someone show how to transform the
above sample queries to collections
and/or cursors?"
The queries you post can be merged into a single statement:
SELECT case when a.column_a IS NULL OR a.column_a = ' '
then b.data_a
else column_a end AS someA,
a.someB,
a.someC
FROM TABLE_A a
left outer join TABLE_B b
on ( a.column_b = b.data_b AND a.column_c = 'C' )
WHERE condition_1 = 'YN756'
AND type_cd = 'P'
AND TO_NUMBER(TO_CHAR(m_date, 'MM')) = '12'
AND (lname LIKE (v_LnameUpper || '%') OR
lname LIKE (v_searchLnameLower || '%'))
AND (e_flag = 'Y' OR
it_flag = 'Y' OR
fit_flag = 'Y'));
(I have simply transposed your logic but that case() statement could be replaced with a neater nvl2(trim(a.column_a), a.column_a, b.data_a) ).
I know you say your queries are more complicated but your first port of call should be to consider rewriting them. I know how seductive it is to break a gnarly query into lots of baby SQLs stitched together with PL/SQL but pure SQL is way more efficient.
To use a collection it is best to define the types in SQL, because it gives us the flexibility to use them in SQL statements as well as PL/SQL.
create or replace type tab_a_row as object
(col_a number
, col_b varchar2(23)
, col_c date);
/
create or replace type tab_a_nt as table of tab_a_row;
/
Here's a sample function, which returns a result set:
create or replace function get_table_a
(p_arg in number)
return sys_refcursor
is
tab_a_recs tab_a_nt;
rv sys_refcursor;
begin
select tab_a_row(col_a, col_b, col_c)
bulk collect into tab_a_recs
from table_a
where col_a = p_arg;
for i in tab_a_recs.first()..tab_a_recs.last()
loop
if tab_a_recs(i).col_b is null
then
tab_a_recs(i).col_b := 'something';
end if;
end loop;
open rv for select * from table(tab_a_recs);
return rv;
end;
/
And here it is in action:
SQL> select * from table_a
2 /
COL_A COL_B COL_C
---------- ----------------------- ---------
1 whatever 13-JUN-10
1 12-JUN-10
SQL> var rc refcursor
SQL> exec :rc := get_table_a(1)
PL/SQL procedure successfully completed.
SQL> print rc
COL_A COL_B COL_C
---------- ----------------------- ---------
1 whatever 13-JUN-10
1 something 12-JUN-10
SQL>
In the function it is necessary to instantiate the type with the columns, in order to avoid the ORA-00947 exception. This is not necessary when populating a PL/SQL table type:
SQL> create or replace procedure pop_table_a
2 (p_arg in number)
3 is
4 type table_a_nt is table of table_a%rowtype;
5 tab_a_recs table_a_nt;
6 begin
7 select *
8 bulk collect into tab_a_recs
9 from table_a
10 where col_a = p_arg;
11 end;
12 /
Procedure created.
SQL>
Finally, guidelines
"What should be the guidelines on When
to use and When to avoid GTT's"
Global temp tables are very good when we need share cached data between different program units in the same session. For instance if we have a generic report structure generated by a single function feeding off a GTT which is populated by one of several procedures. (Although even that could also be implemented with dynamic ref cursors ...)
Global temporary tables are also good if we have a lot of intermediate processing which is just too complicated to be solved with a single SQL query. Especially if that processing must be applied to subsets of the retrieved rows.
But in general the presumption should be that we don't need to use a temporary table. So
Do it in SQL unless it is too hard it which case ...
... Do it in PL/SQL variables (usually collections) unless it takes too much memory it which case ...
... Do it with a Global Temporary Table
Generally I'd use a PL/SQL collection for storing small volumes of data (maybe a thousand rows). If the data volumes were much larger, I'd use a GTT so that they don't overload the process memory.
So I might select a few hundred rows from the database into a PL/SQL collection, then loop through them to do some calculation/delete a few or whatever, then insert that collection into another table.
If I was dealing with hundreds of thousands of rows, I would try to push as much of the 'heavy lifting' processing into large SQL statements. That may or may not require GTT.
You can use SQL level collection objects as something that translates quite easily between SQL and PL/SQL
create type typ_car is object (make varchar2(10), model varchar2(20), year number(4));
/
create type typ_coll_car is table of typ_car;
/
select * from table (typ_coll_car(typ_car('a','b',1999), typ_car('A','Z',2000)));
MAKE MODEL YEAR
---------- -------------------- ---------------
a b 1,999.00
A Z 2,000.00
declare
v_car1 typ_car := typ_car('a','b',1999);
v_car2 typ_car := typ_car('A','Z',2000);
t_car typ_coll_car := typ_coll_car();
begin
t_car := typ_coll_car(v_car1, v_car2);
FOR i in (SELECT * from table(t_car)) LOOP
dbms_output.put_line(i.year);
END LOOP;
end;
/