I'm using Crystal Reports 2013 and have Oracle ODAC 32 and 64 bit versions installed. If I create a new report and use the "Oracle Server" data source, I can select from any tables to which I have access. However, I find I retrieve no data from some, not all, views.
The queries work fine in SQL Plus or SQL Developer. The queries retrieve data in Crystal Reports using outdated drivers like OLE DB and ODBC.
I can't find a commonality between the views that do or don't work. All the views I've tested with belong to the same schema. they all involve tables that belong to a third schema -- that is, I log in as USER1, query from a view belonging to USER2, which pulls data from tables belonging to USER2 and USER3. In order to create a view on a table and make that view available to others, Oracle requires SELECT WITH GRANT OPTION permission, which is in place. Again, the queries work fine in other SQL tools.
UPDATE: I've tried logging in as the owner of the views and was unable to query them. I've tried querying the underlying tables as the view owner (user2) and as the Crystal Reports owner (user1). Both users are able to query the underlying tables. The view itself seems to be the problem.
I'm studying the differences between the views that work and the views that don't work. I was optimistic when I found that the views that don't work were all using ORDER BY clauses that referenced column position (ex: ORDER BY 2, 1). I tried rewriting the ORDER BY to use column names. Didn't work. Tried removing the ORDER BY clauses. Didn't work. Back to the drawing board.
I found that the problem was that the Oracle view was using Oracle-specific, non-standard SQL. In addition to the ORDER BY 2, 1 mentioned above, there was an implicit date conversion in the WHERE clause e.g.
WHERE date_col = '01-JAN-2016'
When I added the TO_DATE function:
WHERE date_col = TO_DATE ('01-JAN-2016', 'dd-MON-yyyy')
Crystal Report was able to query the view.
Related
I’ve been tasked with doing some housekeeping on an Oracle schema I have access to. In a nutshell, I’d like to drop any tables that have not been ‘used’ in the last 3 months (tables that haven’t been queried or had data manipulated in the last 3 months). I have read/write access to the schema but I’m not a DBA; I run relatively basic DML/DDL queries in Oracle.
I’m trying to figure out if there’s a way for me to identify old/redundant tables; here’s what I’ve tried (mostly unsuccessfully)
USER_TABLES was my first port of call, but the LAST_ANALYZED date in this table doesn’t seem to be the last modified/queried date I’m looking for
Googling has brought DBA_Hist tables to my attention, I’ve tried querying some of these (i.e. DBA_HIST_SYSSTAT) but I’m confronted with (ORA-00942: table or view does not exist)
I’ve also tried querying V$SESSION_WAIT, V$ACTIVE_SESSION_HISTORY and V$SEGMENT_STATISTICS, but I get the same ORA-00942 error
I’d be grateful for any advice about whether the options above actually offer the sort of information I need about tables, and if so what I can do to work around the errors I’m getting. Alternatively, are there any other options that I could explore?
Probably the easiest thing to do, to be 100% sure, is to enable auditing on the Oracle tables that you're interested in (possibly all of them). Once enabled, Oracle has an audit table (dba_audit_trail) that you can query to find if the table(s) have been accessed. You can enable auditing by issuing: AUDIT on . BY SESSION;
I chose "by session" so that you only get a single record per session, no matter how many times the session performs the operation (to minimize the records in the audit table).
Example:
audit select on bob.inventory by session;
Then you can query the dba_audit_trail after some time passes to see if any records show up for that table.
You can disable auditing by issuing the "noaudit" command.
Hope that helps.
-Jim
I am developing a java app which can connect to oracle database and selecting column names from any tables, after selecting columns i have to query the data from those tables which the user select in my java app, now my question is how can i join all tables in the database so that query returns data successfully, i want to connect to any oracle schema to a specific, i will make the logic in java, but i am unable to find the query which can extract the data from all tables, i tried natural join among all tables but it has dependency of having same name of connecting columns. so i want to know any generic way which can work in all conditions.
As others have mentioned.. it seems that there are other tools out there that you probably should leverage prior to trying to roll your own complex solution.
With that said if you wish to roll your own solution you could look into using some of oracle's dictionary tables. Such as:
Select * from all_tables;
Select * from all_tab_cols;
We have a legacy app that I am rewriting in .net. All of our databases are oracle and make use of database links. Is there any way for Entity Framework 6 to generate models based on tables located on a different database?
Currently the legacy app gets data from table like this
SELECT * FROM emp#foo2;
where its db connection is to database foo that has a database link to the database foo2.
I would like to reproduce this using EF6. So far all I have found regarding this is this question.
You can do two things that EF 4 or higher will work with:
CREATE VIEW EMP as SELECT * FROM emp#foo2;
CREATE MATERIALIZED VIEW EMP as SELECT * FROM emp#foo2;
LOBS are not accessible across a database link without some contorted PL/SQL processing to read the LOB piece by piece.
I believe fast refresh does not work across database links so you must consider the size of the table on the linked database. If you are refreshing a million rows you may find the time to do this is an issue. Most large tables are full of tombstone data that never changes so a timestamp column with the last modified date could help you create a package that only picks out the changed data.
If you are doing complicated joins for either ensure that Oracle considers the column that would be the primary key as not null.
You can add a primary key on views and materialized view but it must be disabled. See here for details.
I would like to create a cached copy of a table via dblink in oracle. The story is the following:
I have two tables (employee, work) which are joined via a third table (emloyee_work) in a remote database. The reason for that is to decouple the connection between the two entities so that they are not able to be connected directly.
To handle the data easily we have a view that connects the tables via the join table. One can argue that this is the same as having the join table in the same database as the other two but that in not the point right now.
On a new site, the db link latency is very high which causes a major drop in performance since for every select the view is built and a select is executed for each employee through the db link.
The structure has relative high read count and low write count.
The question is whether there is a possibility to "mirror" or copy the remote join table to the local database? This copy should be temporary and should not be persisted.
This way the view would be executed on the local copy.
EDIT: Oracle version is 11gR2
You could use refreshed on demand materialized views.
See also this link where they talk about implementing a materialized view over a dblink.
Since you are using Oracle 11g, you may create an ad-hoc, RAM-based Materialized View.
We have some Materialized views in our Oracle 9i database that were created a long time ago, by a guy no longer working here. Is there an easy (or any) method to determine whether Oracle is using these views to serve queries? If they aren't being used any more, we'd like to get rid of them. But we don't want to discover after the fact that those views are the things that allow some random report to run in less than a few hours. The answer I'm dreaming of would be something like
SELECT last_used_date FROM dba_magic
WHERE materialized_view_name = 'peters_mview'
Even more awesome would be something that could tell me what actual SQL queries were using the materialized view. I realize I may have to settle for less.
If there is a solution that requires 10g, we are upgrading soon, so those answers would be useful also.
Oracle auditing can tell you this once configured as per the docs. Once configured, enable it by "AUDIT SELECT ON {name of materialized view}". The audit trail will be in the AUD$ table in the SYS schema.
One method other than auditing would be to read the v$segment_statistics view after one refresh and before the next refresh to see if there have been any reads. You'd have to account for any automatic statistics collection jobs also.
V$SQLAREA table has two columns which help identify the queries executed by the database.
SQL_TEXT - VARCHAR2(1000) - First thousand characters of the SQL text for the current cursor
SQL_FULLTEXT - CLOB - All characters of the SQL text for the current cursor
We can use this columns to find the queries using the said materialized views