I have some code that runs the same query in 2 different databases.
SELECT
P.MYID,
CASE WHEN
SUBSTR(P.MYID, 1, 1) NOT IN ('W') THEN
'YOUR_ID_IS_NOT_START_WITH_W'
ELSE
(SELECT OTHER_ID FROM PERSON WHERE NUMBER = '2554' )
END AS "ALTERNATE_ID"
FROM
PERS_INFO P
WHERE
P.NUMBER = '2554'
OTHER_ID in this example is a column that only exists in the 2nd database. Thats completely fine because the query will only execute in the 1st database when the id DOES NOT start with 'W'. In otherwords, this query will only ever run in the 1st database, when the MYID does not start with 'W' and will only ever run in the 2nd database when MYID does start with 'W'.
So the query would work in both databases, however, the query fails with an ORA-00904 in the first database because it says OTHER_ID is not legal in the first database (which is true, but i dont care). how do i force oracle to run the query anyways or work around this?
You could create a function in both databases to get the OTHER_ID value. It would just return null in your first database.
For example, in the first database:
create or replace function f_get_other_id(for_no in varchar2) return varchar2 is
begin
return null;
end;
In the second database:
create or replace function f_get_other_id(for_no in varchar2) return varchar2 is
v_other_id varchar2(100);
begin
select other_id into v_other_id from person where number = for_no;
return other_id;
end;
Then, your query can be:
select p.myid,
case
when substr(p.myid, 1, 1) not in ('W') then 'YOUR_ID_IS_NOT_START_WITH_W'
else f_get_other_id('2554')
end as "ALTERNATE_ID"
from pers_info p
where p.number = '2554'
Have you heard about the EXECUTE_IMMEDIATE (http://docs.oracle.com/cd/B19306_01/appdev.102/b14261/executeimmediate_statement.htm) command or about DBMS_SQL (see http://docs.oracle.com/cd/B28359_01/appdev.111/b28419/d_sql.htm)?
If you are working with scripts on various databases that have different tables definition, this might be the solution for you, though this requires PL/SQL.
I'm not sure what the problem would be with adding this column to the database that it is currently absent from, but adding it seems like a pretty low effort and low risk exercise, and would permanently solve this kind of problem.
Probably you need to add another CASE after else checking the database name. Case db_name = db_name1 then your other_id query else some other query lk select 1 from dual... You can get db_name from v$database view.
Related
We have a large amount of data in an Oracle 11g server. Most of the engineers use Tableau for visualizing data, but there is currently not a great solution for visualizing straight from the Oracle server because of the structure of the database. Unfortunately, this cannot be changed, as it's very deeply integrated with the rest of our systems. There is a "dictionary" table, let's call it tab_keys:
name | key
---------------
AB-7 | 19756
BG-0 | 76519
FY-10 | 79513
JB-2 | 18765
...
...
And there are also the tables actually containing the data. Each entry in tab_keys has a corresponding data table named by prefixing the key with an identifier, in this case, we'll use "dat_". So AB-7 will store all its data in a table called dat_19756. These keys are not known to the user, and are only used for tracking "behind the scenes". The user only knows the AB-7 moniker.
Tableau allows communication with Oracle servers using standard SQL select statements, but because the user doesn't know the key value, they cannot write a SQL statement to query the data.
Tableau recently added the ability for users to query Oracle Table Functions, so I started going down the road of writing a table function to query for the key, and return a table of the results for Tableau to use. The problem is that each dat_ table is basically unique with a different numbers of columns, labels, number of records, and datatypes from the next dat_ table.
What is the right way to handle this problem? Can I:
1) Write a function (which tableau can call inline in regular SQL) to return a bonified table name which is dynamically generated? I tried this:
create or replace FUNCTION TEST_FUNC
(
V_NAME IN VARCHAR2
) RETURN user_tables.table_name%type AS
V_KEY VARCHAR(100);
V_TABLE user_tables.table_name%type;
BEGIN
select KEY into V_KEY from my_schema.tab_keys where NAME = V_NAME;
V_TABLE := dbms_assert.sql_object_name('my_schema.dat_' || V_KEY);
RETURN V_TABLE;
END TEST_FUNC;
and then SELECT * from TABLE(TEST_FUNC('AB-7')); but I get:
ORA-22905: cannot access rows from a non-nested table item
22905. 00000 - "cannot access rows from a non-nested table item"
*Cause: attempt to access rows of an item whose type is not known at
parse time or that is not of a nested table type
*Action: use CAST to cast the item to a nested table type
I couldn't figure out a good way to CAST the table as the table type I needed. Could this be done in the function before returning?
2) Write a table function? Tableau can supposedly query these like tables, but then I run into the problem of dynamically generating types (which I understand isn't easy) but with the added complication of this needing to be used by multiple users simultaneously, so each user would need a data type generated for them each time they connect to a table (if I'm understanding this correctly).
I have to think I'm missing something simple. How do I cast the return of this query as this other table's datatype?
There is no simple way to have a single generic function return a dynamically configurable nested table. With other products you could use a Ref Cursor (which maps to ODBC or JDBC ResultSet object) but my understanding is Tableau does not support that option.
One thing you can do is generate views from your data dictionary. You can use this query to produce a one-off script.
select 'create or replace view "' || name || '" as select * from dat_' || key || ';'
from tab_keys;
The double-quotes are necessary because AB-7 is not a valid object name in Oracle, due to the dash.
This would allow your users to query their data like this:
select * from "AB-7";
Note they would have to use the double-quotes too.
Obviously, any time you inserted a row in tab_keys you'd need to create the required view. That could be done through a trigger.
You can build dynamic SQL in SQL using the open source program Method4:
select * from table(method4.dynamic_query(
q'[
select 'select * from dat_'||key
from tab_keys
where name = 'AB-7'
]'
));
A
-
1
The program combines Oracle Data Cartridge Interface with ANYDATASET to create a function that can return dynamic types.
There might be a way to further simplify the interface but I haven't figured it out yet. These Oracle Data Cartridge Interface functions are very picky and are not easy to repackage.
Here's the sample schema I used:
create table tab_keys(name varchar2(100), key varchar2(100));
insert into tab_keys
select 'AB-7' , '19756' from dual union all
select 'BG-0' , '76519' from dual union all
select 'FY-10', '79513' from dual union all
select 'JB-2' , '18765' from dual;
create table dat_19756 as select 1 a from dual;
create table dat_76519 as select 2 b from dual;
create table dat_79513 as select 3 c from dual;
create table dat_18765 as select 4 d from dual;
Im trying to create a function which takes in 3 parameters and returns one. The value of the returned parameter is obtained by querying two tables, however, one of the tables is on a different schema. The SQL im using is below:
create or replace FUNCTION tester
(
originaltext IN VARCHAR2, lang IN VARCHAR2, category IN VARCHAR2 DEFAULT NULL)
RETURN VARCHAR2 AS
translatedttextval VARCHAR2(255) := '';
BEGIN
--if category is null, disregard category
if category is null then
SELECT distinct nvl(trans.translatedtext, originaltext)
INTO translatedttext
FROM tbl_translations trans, SECDEVSCHEMA.tbl_instanceids ids
WHERE trans.translatedlang = ids.id_a
AND ids.name = lang
AND trans.originaltext = originaltext;
end if;
RETURN translatedttextval;
END;
I've removed a bit of the query here which searches with category because it does something similar and has the same issue.
So, when I run this and pass in the params, I get an error which reads:
Error(16,46): PL/SQL: ORA-00942: table or view does not exist
If I do the following query it works fine when not on the SECDEVSCHEMA and returns the reults from tbl_instanceids which is on the SECDEVSCHEMA schema:
SELECT * FROM SECDEVSCHEMA.tbl_instanceids ids WHERE ids.id_a = 1234555;
I don't have DBA access to the DB but if I need some select priviledge granted or something I can get it done. Not sure if this the case though as the above query works.
Small additional question also:
where it says in the query
nvl(trans.translatedtext, originaltext)
If i wanted to surround the original text value with brackets when no translatedtext value exists, how would I go about this?
I'm using SQL Developer by the way in case that's important.
Thanks
for your smaller question
nvl(trans.translatedtext, '<'|| originaltext ||'>' )
This was down to a priviledges issue.
In SQL Developer, I expanded the tables package and selected the table I needed access to in the Function, right clicked and selected Priviledges > Grant.
As this is just a Development DB I just assigned all the priviledges to the appropriate schema or User and its working now.
Still unsure about this part though:
Small additional question also: where it says in the query nvl(trans.translatedtext, originaltext)
If i wanted to surround the original text value with brackets when no translatedtext value exists, how would >I go about this?
Any takers for this?
Thanks
I have a set of 4 tables that contain different partitions of some data. I also have a plpgsql function that will take an id and return the name of the table containing that data as a 'character varying'.
However, when I try to use this function to select from the correct table, e.g.
SELECT f.a FROM getTable(someID) AS f;
it doesn't seem to work. It doesn't throw an error on the SELECT, but it doesn't return the fields I'm expecting either (i.e. it says f.a doesn't exist).
How do I select data from a table where the table name is given by the return of a function?
I'm using PostgreSQL 9.1. This is going to be run over millions of records, so I don't want to have to do it as two separate calls.
I think for the problem described in the topic you should use inheritance with tables.
Answering the question - use execute:
execute "SELECT f.a FROM " || getTable(someID) || " AS f";
I'd like to get all the records from a huge table where any of the number columns countains a value greater than 0. What's the best way to do it?
E.g.:
/* table structure*/
create table sometable (id number,
somestring varchar2(12),
some_amount_1 number(17,3),
some_amount_2 number(17,3),
some_amount_3 number(17,3),
...
some_amount_xxx number(17,3));
/* "xxx" > 100, and yeah I did not designed that table structure... */
And I want any row where any of the some_amount_n > 0 (even better solution is to add a field in the first place to show which field(s) are greater than zero).
I know I can write this with a huge some_amount_1 > 0 OR some_amount_2 > 0 OR ... block (and the field names with some case when but is there should be some more elegant solution, isn't there?
Possible solutions:
Normalize the table. You said you are not allowed to. Try to convince those that forbid such a change by explaining the benefits (performance, ease of writing queries, etc).
Write the huge ugly OR query. You could also print it along with the version of the query for the normalized tables. Add performance tests (you are allowed to create another test table or database, I hope.)
Write a program (either in PL/SQL or in another procedural language) that produces the horrible OR query. (Again, print along with the elegant version)
Add a new column, say called Any_x_bigger_than_zero which is automatically filled with either 0 or 1 via a trigger (that uses a huge ugly OR). Then you just need to check: WHERE Test_x_bigger_than_zero = 1 to see if any of the rows is > 0
Similar to previous but even better, create a materialized view with such a column.
First, create a table to sort the data into something more easily read from...something simple like id,column_name,column_value. You'll have to bear with me, been a while since I've operated in oracle, so this is heavy pseudo code at best:
Quick dynamic sql blurb...you can set a variable to a sql statement and then execute that variable. There are some security risks and it's possible this feature is disabled in your environment...so confirm you can run this first. Declare a variable, set the variable to 'select 1' and then use 'execute immediate' to execute the sql stored in your variable.
set var = 'select id, ''some_amount_' || 1 || '', some_amount || 1 || ' from table where some_amount_' || 1 || ' <> 0'
Assuming I've got my oracle syntax right...( pipe is append right? I believe a 3 single quote as ''' should result in one ' when in a variable too, you may have to trial and error this line until you have the var set to):
select id, 'some_amount_1',some_amount_1
from table
where some_amount_1 <> 0
This should select the ID and the value in some_amount_1 for each id in your database. You can turn this into an insert statement pretty easily.
I'm assuming some_amount_xxx has an upper limit...next trick is to loop this giant statement. Once again, horrible pseudo code:
declare sql_string
declare i and set to 1
for i = 1 to xxx (whatever your xxx is)
set sql_string to the first set var statement we made, replacing the '1' with the i var here.
execute sql
increment i
loop
Hopefully it makes sense...it's one of the very few scenarios you would ever want to loop dynamic sql on. Now you have a relatively straight forward table to read from and this should be a relatively easy query from here
I would like to return the ids which have been deleted by a DELETE query.
On Stackoverlow, I found this:
How to get ID of the last updated row in MySQL?
The top1 answer has a very nice solution, but it's for mysql. I tried to do the same in Firebird after reading some part of the Firebird manual:
set term ^ ;
EXECUTE BLOCK
AS
DECLARE VARIABLE uids BLOB SUB_TYPE TEXT;
begin
DELETE FROM CATEGORY WHERE name = 'Haló'
AND ( SELECT id INTO :uids );
SELECT #uids;
end
^
Yes, I know that 'uids' will always contain one ID, since I'm overwriting the variable, but it's only a test, and what is more, it doesn't work. It stops at 'INTO' saying "Token unknown - line 8, column 21". I don't know what to do, what to continue with.. :\
Thanks for Your help!
For this, please run separate queries
First fetch the record ids those you want to delete by the same where condition for DELETE
like, SELECT ID FROM CATEGORY WHERE name = 'Haló'
Then delete the records
you could try the "RETURNING" clause, like this:
delete from Scholars
where firstname = 'Henry' and lastname = 'Higgins'
returning lastname, fullname, id
look here for more details