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 (and don't own, so I can't change) a table with a layout similar to this.
ID | CATEGORIES
---------------
1 | c1
2 | c2,c3
3 | c3,c2
4 | c3
5 | c4,c8,c5,c100
I need to return the rows that contain a specific category id. I starting by writing the queries with LIKE statements, because the values can be anywhere in the string
SELECT id FROM table WHERE categories LIKE '%c2%';
Would return rows 2 and 3
SELECT id FROM table WHERE categories LIKE '%c3%' and categories LIKE '%c2%'; Would again get me rows 2 and 3, but not row 4
SELECT id FROM table WHERE categories LIKE '%c3%' or categories LIKE '%c2%'; Would again get me rows 2, 3, and 4
I don't like all the LIKE statements. I've found FIND_IN_SET() in the Oracle documentation but it doesn't seem to work in 10g. I get the following error:
ORA-00904: "FIND_IN_SET": invalid identifier
00904. 00000 - "%s: invalid identifier"
when running this query: SELECT id FROM table WHERE FIND_IN_SET('c2', categories); (example from the docs) or this query: SELECT id FROM table WHERE FIND_IN_SET('c2', categories) <> 0; (example from Google)
I would expect it to return rows 2 and 3.
Is there a better way to write these queries instead of using a ton of LIKE statements?
You can, using LIKE. You don't want to match for partial values, so you'll have to include the commas in your search. That also means that you'll have to provide an extra comma to search for values at the beginning or end of your text:
select
*
from
YourTable
where
',' || CommaSeparatedValueColumn || ',' LIKE '%,SearchValue,%'
But this query will be slow, as will all queries using LIKE, especially with a leading wildcard.
And there's always a risk. If there are spaces around the values, or values can contain commas themselves in which case they are surrounded by quotes (like in csv files), this query won't work and you'll have to add even more logic, slowing down your query even more.
A better solution would be to add a child table for these categories. Or rather even a separate table for the catagories, and a table that cross links them to YourTable.
You can write a PIPELINED table function which return a 1 column table. Each row is a value from the comma separated string. Use something like this to pop a string from the list and put it as a row into the table:
PIPE ROW(ltrim(rtrim(substr(l_list, 1, l_idx - 1),' '),' '));
Usage:
SELECT * FROM MyTable
WHERE 'c2' IN TABLE(Util_Pkg.split_string(categories));
See more here: Oracle docs
Yes and No...
"Yes":
Normalize the data (strongly recommended) - i.e. split the categorie column so that you have each categorie in a separate... then you can just query it in a normal faschion...
"No":
As long as you keep this "pseudo-structure" there will be several issues (performance and others) and you will have to do something similar to:
SELECT * FROM MyTable WHERE categories LIKE 'c2,%' OR categories = 'c2' OR categories LIKE '%,c2,%' OR categories LIKE '%,c2'
IF you absolutely must you could define a function which is named FIND_IN_SET like the following:
CREATE OR REPLACE Function FIND_IN_SET
( vSET IN varchar2, vToFind IN VARCHAR2 )
RETURN number
IS
rRESULT number;
BEGIN
rRESULT := -1;
SELECT COUNT(*) INTO rRESULT FROM DUAL WHERE vSET LIKE ( vToFine || ',%' ) OR vSET = vToFind OR vSET LIKE ('%,' || vToFind || ',%') OR vSET LIKE ('%,' || vToFind);
RETURN rRESULT;
END;
You can then use that function like:
SELECT * FROM MyTable WHERE FIND_IN_SET (categories, 'c2' ) > 0;
For the sake of future searchers, don't forget the regular expression way:
with tbl as (
select 1 ID, 'c1' CATEGORIES from dual
union
select 2 ID, 'c2,c3' CATEGORIES from dual
union
select 3 ID, 'c3,c2' CATEGORIES from dual
union
select 4 ID, 'c3' CATEGORIES from dual
union
select 5 ID, 'c4,c8,c5,c100' CATEGORIES from dual
)
select *
from tbl
where regexp_like(CATEGORIES, '(^|\W)c3(\W|$)');
ID CATEGORIES
---------- -------------
2 c2,c3
3 c3,c2
4 c3
This matches on a word boundary, so even if the comma was followed by a space it would still work. If you want to be more strict and match only where a comma separates values, replace the '\W' with a comma. At any rate, read the regular expression as:
match a group of either the beginning of the line or a word boundary, followed by the target search value, followed by a group of either a word boundary or the end of the line.
As long as the comma-delimited list is 512 characters or less, you can also use a regular expression in this instance (Oracle's regular expression functions, e.g., REGEXP_LIKE(), are limited to 512 characters):
SELECT id, categories
FROM mytable
WHERE REGEXP_LIKE('c2', '^(' || REPLACE(categories, ',', '|') || ')$', 'i');
In the above I'm replacing the commas with the regular expression alternation operator |. If your list of delimited values is already |-delimited, so much the better.
I am recieving information from a csv file from one department to compare with the same inforation in a different department to check for discrepencies (About 3/4 of a million rows of data with 44 columns in each row). After I have the data in a table, I have a program that will take the data and send reports based on a HQ. I feel like the way I am going about this is not the most efficient. I am using oracle for this comparison.
Here is what I have:
I have a vb.net program that parses the data and inserts it into an extract table
I run a procedure to do a full outer join on the two tables into a new table with the fields in one department prefixed with '_c'
I run another procedure to compare the old/new data and update 2 different tables with detail and summary information. Here is code from inside the procedure:
DECLARE
CURSOR Cur_Comp IS SELECT * FROM T.AEC_CIS_COMP;
BEGIN
FOR compRow in Cur_Comp LOOP
--If service pipe exists in CIS but not in FM and the service pipe has status of retired in CIS, ignore the variance
If(compRow.pipe_num = '' AND cis_status_c = 'R')
continue
END IF
--If there is not a summary record for this HQ in the table for this run, create one
INSERT INTO t.AEC_CIS_SUM (HQ, RUN_DATE)
SELECT compRow.HQ, to_date(sysdate, 'DD/MM/YYYY') from dual WHERE NOT EXISTS
(SELECT null FROM t.AEC_CIS_SUM WHERE HQ = compRow.HQ AND RUN_DATE = to_date(sysdate, 'DD/MM/YYYY'))
-- Check fields and update the tables accordingly
If (compRow.cis_loop <> compRow.cis_loop_c) Then
--Insert information into the details table
INSERT INTO T.AEC_CIS_DET( Fac_id, Pipe_Num, Hq, Address, AutoUpdatedFl,
DateTime, Changed_Field, CIS_Value, FM_Value)
VALUES(compRow.Fac_ID, compRow.Pipe_Num, compRow.Hq, compRow.Street_Num || ' ' || compRow.Street_Name,
'Y', sysdate, 'Cis_Loop', compRow.cis_loop, compRow.cis_loop_c);
-- Update information into the summary table
UPDATE AEC_CIS_SUM
SET cis_loop = cis_loop + 1
WHERE Hq = compRow.Hq
AND Run_Date = to_date(sysdate, 'DD/MM/YYYY')
End If;
END LOOP;
END;
Any suggestions of an easier way of doing this rather than an if statement for all 44 columns of the table? (This is run once a week if it matters)
Update: Just to clarify, there are 88 columns of data (44 of duplicates to compare with one suffixed with _c). One table lists each field in a row that is different so one row can mean 30+ records written in that table. The other table keeps tally of the number of discrepencies for each week.
First of all I believe that your task can be implemented (and should be actually) with staight SQL. No fancy cursors, no loops, just selects, inserts and updates. I would start with unpivotting your source data (it is not clear if you have primary key to join two sets, I guess you do):
Col0_PK Col1 Col2 Col3 Col4
----------------------------------------
Row1_val A B C D
Row2_val E F G H
Above is your source data. Using UNPIVOT clause we convert it to:
Col0_PK Col_Name Col_Value
------------------------------
Row1_val Col1 A
Row1_val Col2 B
Row1_val Col3 C
Row1_val Col4 D
Row2_val Col1 E
Row2_val Col2 F
Row2_val Col3 G
Row2_val Col4 H
I think you get the idea. Say we have table1 with one set of data and the same structured table2 with the second set of data. It is good idea to use index-organized tables.
Next step is comparing rows to each other and storing difference details. Something like:
insert into diff_details(some_service_info_columns_here)
select some_service_info_columns_here_along_with_data_difference
from table1 t1 inner join table2 t2
on t1.Col0_PK = t2.Col0_PK
and t1.Col_name = t2.Col_name
and nvl(t1.Col_value, 'Dummy1') <> nvl(t2.Col_value, 'Dummy2');
And on the last step we update difference summary table:
insert into diff_summary(summary_columns_here)
select diff_row_id, count(*) as diff_count
from diff_details
group by diff_row_id;
It's just rough draft to show my approach, I'm sure there is much more details should be taken into account. To summarize I suggest two things:
UNPIVOT data
Use SQL statements instead of cursors
You have several issues in your code:
If(compRow.pipe_num = '' AND cis_status_c = 'R')
continue
END IF
"cis_status_c" is not declared. Is it a variable or a column in AEC_CIS_COMP?
In case it is a column, just put the condition into the cursor, i.e. SELECT * FROM T.AEC_CIS_COMP WHERE not (compRow.pipe_num = '' AND cis_status_c = 'R')
to_date(sysdate, 'DD/MM/YYYY')
That's nonsense, you convert a date into a date, simply use TRUNC(SYSDATE)
Anyway, I think you can use three single statements instead of a cursor:
INSERT INTO t.AEC_CIS_SUM (HQ, RUN_DATE)
SELECT comp.HQ, trunc(sysdate)
from AEC_CIS_COMP comp
WHERE NOT EXISTS
(SELECT null FROM t.AEC_CIS_SUM WHERE HQ = comp.HQ AND RUN_DATE = trunc(sysdate));
INSERT INTO T.AEC_CIS_DET( Fac_id, Pipe_Num, Hq, Address, AutoUpdatedFl, DateTime, Changed_Field, CIS_Value, FM_Value)
select comp.Fac_ID, comp.Pipe_Num, comp.Hq, comp.Street_Num || ' ' || comp.Street_Name, 'Y', sysdate, 'Cis_Loop', comp.cis_loop, comp.cis_loop_c
from T.AEC_CIS_COMP comp
where comp.cis_loop <> comp.cis_loop_c;
UPDATE AEC_CIS_SUM
SET cis_loop = cis_loop + 1
WHERE Hq IN (Select Hq from T.AEC_CIS_COMP)
AND trunc(Run_Date) = trunc(sysdate);
They are not tested but they should give you a hint how to do it.
A weird request maybe but. My boss wants me to create an admin version of a page we have that displays data from an oracle query in a table.
The admin page, instead of displaying the data (query returns 1 row), needs to return the table name and column name
Ex: Instead of:
Name Initial
==================
Bob A
I want:
Name Initial
============================
Users.FirstName Users.MiddleInitial
I realize I can do this in code but would rather just modify the query to return the data I want so I can leave the report generation code mostly alone.
I don't want to do it in a stored procedure.
So when I spit out the data in the report using something like:
blah blah = MyDataRow("FirstName")
I can leave that as is but instead of it displaying "BOB" it would display "Users.FirstName"
And I want to do the query using select * if possible instead of listing all the columns
So for each of the columns I am querying in the * , I want to get (instead of the column value) the tablename.ColumnName or tablename|columnName
hope you are following- I am confusing myself...
pseudo:
select tablename + '.' + Columnname as WhateverTheColumnNameIs
from Table1
left join Table2 on whatever...
Join Table_Names on blah blah
Whew- after writing all this I think I will just do it on the code side.
But if you are up for it maybe a fun challenge
Oracle does not provide an authentic way(there is no pseudocolumn) to get the column name of a table as a result of a query against that table. But you might consider these two approaches:
Extract column name from an xmltype, formed by passing cursor expression(your query) in the xmltable() function:
-- your table
with t1(first_name, middle_name) as(
select 1,2 from dual
), -- your query
t2 as(
select * -- col1 as "t1.col1"
--, col2 as "t1.col2"
--, col3 as "t1.col3"
from hr.t1
)
select *
from ( select q.object_value.getrootelement() as col_name
, rownum as rn
from xmltable('//*'
passing xmltype(cursor(select * from t2 where rownum = 1))
) q
where q.object_value.getrootelement() not in ('ROWSET', 'ROW')
)
pivot(
max(col_name) for rn in (1 as "name", 2 as "initial")
)
Result:
name initial
--------------- ---------------
FIRST_NAME MIDDLE_NAME
Note: In order for column names to be prefixed with table name, you need to list them
explicitly in the select list of a query and supply an alias, manually.
PL/SQL approach. Starting from Oracle 11g you could use dbms_sql() package and describe_columns() procedure specifically to get the name of columns in the cursor(your select).
This might be what you are looking for, try selecting from system views USER_TAB_COLS or ALL_TAB_COLS.
I am developing an application in Oracle APEX. I have a string with user id's that is comma deliminated which looks like this,
45,4932,20,19
This string is stored as
:P5_USER_ID_LIST
I want a query that will find all users that are within this list my query looks like this
SELECT * FROM users u WHERE u.user_id IN (:P5_USER_ID_LIST);
I keep getting an Oracle error: Invalid number. If I however hard code the string into the query it works. Like this:
SELECT * FROM users u WHERE u.user_id IN (45,4932,20,19);
Anyone know why this might be an issue?
A bind variable binds a value, in this case the string '45,4932,20,19'. You could use dynamic SQL and concatenation as suggested by Randy, but you would need to be very careful that the user is not able to modify this value, otherwise you have a SQL Injection issue.
A safer route would be to put the IDs into an Apex collection in a PL/SQL process:
declare
array apex_application_global.vc_arr2;
begin
array := apex_util.string_to_table (:P5_USER_ID_LIST, ',');
apex_collection.create_or_truncate_collection ('P5_ID_COLL');
apex_collection.add_members ('P5_ID_COLL', array);
end;
Then change your query to:
SELECT * FROM users u WHERE u.user_id IN
(SELECT c001 FROM apex_collections
WHERE collection_name = 'P5_ID_COLL')
An easier solution is to use instr:
SELECT * FROM users u
WHERE instr(',' || :P5_USER_ID_LIST ||',' ,',' || u.user_id|| ',', 1) !=0;
tricks:
',' || :P5_USER_ID_LIST ||','
to make your string ,45,4932,20,19,
',' || u.user_id|| ','
to have i.e. ,32, and avoid to select the 32 being in ,4932,
I have faced this situation several times and here is what i've used:
SELECT *
FROM users u
WHERE ','||to_char(:P5_USER_ID_LIST)||',' like '%,'||to_char(u.user_id)||',%'
ive used the like operator but you must be a little carefull of one aspect here: your item P5_USER_ID_LIST must be ",45,4932,20,19," so that like will compare with an exact number "',45,'".
When using it like this, the select will not mistake lets say : 5 with 15, 155, 55.
Try it out and let me know how it goes;)
Cheers ,
Alex
Create a native query rather than using "createQuery/createNamedQuery"
The reason this is an issue is that you cannot just bind an in list the way you want, and just about everyone makes this mistake at least once as they are learning Oracle (and probably SQL!).
When you bind the string '32,64,128', it effectively becomes a query like:
select ...
from t
where t.c1 in ('32,64,128')
To Oracle this is totally different to:
select ...
from t
where t.c1 in (32,64,128)
The first example has a single string value in the in list and the second has a 3 numbers in the in list. The reason you get an invalid number error is because Oracle attempts to cast the string '32,64,128' into a number, which it cannot do due to the commas in the string.
A variation of this "how do I bind an in list" question has come up on here quite a few times recently.
Generically, and without resorting to any PLSQL, worrying about SQL Injection or not binding the query correctly, you can use this trick:
with bound_inlist
as
(
select
substr(txt,
instr (txt, ',', 1, level ) + 1,
instr (txt, ',', 1, level+1) - instr (txt, ',', 1, level) -1 )
as token
from (select ','||:txt||',' txt from dual)
connect by level <= length(:txt)-length(replace(:txt,',',''))+1
)
select *
from bound_inlist a, users u
where a.token = u.id;
If possible the best idea may be to not store your user ids in csv! Put them in a table or failing that an array etc. You cannot bind a csv field as a number.
Please dont use: WHERE ','||to_char(:P5_USER_ID_LIST)||',' like '%,'||to_char(u.user_id)||',%' because you'll force a full table scan although with the users table you may not have that many so the impact will be low but against other tables in an enterprise environment this is a problem.
EDIT: I have put together a script to demonstrate the differences between the regex method and the wildcard like method. Not only is regex faster but it's also a lot more robust.
-- Create table
create table CSV_TEST
(
NUM NUMBER not null,
STR VARCHAR2(20)
);
create sequence csv_test_seq;
begin
for j in 1..10 loop
for i in 1..500000 loop
insert into csv_test( num, str ) values ( csv_test_seq.nextval, to_char( csv_test_seq.nextval ));
end loop;
commit;
end loop;
end;
/
-- Create/Recreate primary, unique and foreign key constraints
alter table CSV_TEST
add constraint CSV_TEST_PK primary key (NUM)
using index ;
alter table CSV_TEST
add constraint CSV_TEST_FK unique (STR)
using index;
select sysdate from dual;
select *
from csv_test t
where t.num in ( Select Regexp_Substr('100001, 100002, 100003 , 100004, 100005','[^,]+', 1, Level) From Dual
Connect By Regexp_Substr('100001, 100002,100003, 100004, 100005', '[^,]+', 1, Level) Is Not Null);
select sysdate from dual;
select *
from csv_test t
where ('%,' || '100001,100002, 100003, 100004 ,100005' || ',%') like '%,' || num || ',%';
select sysdate from dual;
select *
from csv_test t
where t.num in ( Select Regexp_Substr('100001, 100002, 100003 , 100004, 100005','[^,]+', 1, Level) From Dual
Connect By Regexp_Substr('100001, 100002,100003, 100004, 100005', '[^,]+', 1, Level) Is Not Null);
select sysdate from dual;
select *
from csv_test t
where ('%,' || '100001,100002, 100003, 100004 ,100005' || ',%') like '%,' || num || ',%';
select sysdate from dual;
drop table csv_test;
drop sequence csv_test_seq;
Solution from Tony Andrews works for me. The process should be added to "Page processing" >> "After submit">> "Processes".
As you are Storing User Ids as String so You can Easily match String Using Like as Below
SELECT * FROM users u WHERE u.user_id LIKE '%'||(:P5_USER_ID_LIST)||'%'
For Example
:P5_USER_ID_LIST = 45,4932,20,19
Your Query Surely Will return Any of 1 User Id which Matches to Users table
This Will Surely Resolve Your Issue , Enjoy
you will need to run this as dynamic SQL.
create the entire string, then run it dynamically.