Oracle dynamic database link from variables - database

i have 3 oracle databases: db1, db2, db3.
I have created database links from db1 to db2 and db3, called db002link and db003link.
Now i have a procedure which takes as input a date and takes different actions on tables according to that input. One of them though requires to connect to one of the db2 or db3 databases. Before the execution of the procedure, i don't not know to which one, as it depends on the data gathered by the procedure itself in previous steps.
So i need to concatenate some variables to create the db link and then connect through it.
i have the variable v_dbnumber which is varchar(3) and looks like '003' for instance and is the result of a select from a table. I have tried the following:
v_dbconn := 'db'||v_dbnumber||'link'
But then the next step, select * from s1.t1#v_dbconn gets a compilation error for the procedure: ORA-04052, ORA-00604, ORA-02019 referring to the non existing connection. But the object is shown as:
#v_dbconn instead of #db003link.
Can somebody please help me with this?

If you need the statement to be dynamic, you'd need to use dynamic SQL.
If you just want to open a cursor using a dynamically generated SQL statement, you can do something like
DECLARE
l_sql_stmt varchar2(1000);
l_dblink varchar2(100) := 'db002link';
l_rc sys_refcursor;
BEGIN
l_sql := 'select * from s1.t1#' || l_dblink;
open l_rc for l_sql;
END;
Normally, though, you're doing something with the data that you're selecting. That would generally involve using either dbms_sql or EXECUTE IMMEDIATE to execute the statement and fetch data into some local variable or collection. Assuming that the table definitions are the same in each of the databases, you could do something like
EXECUTE IMMEDIATE l_sql
BULK COLLECT INTO <<some appropriate collection>>

My solution is very similar to Justin's, though I am using a procedure with dynamic sql.
APPS#tst> CREATE OR REPLACE PROCEDURE test_dblink(
2 db_link VARCHAR2 )
3 AS
4 v_sql VARCHAR2(500);
5 v_test dual.dummy%TYPE;
6 BEGIN
7 v_sql := 'select dummy from dual#'|| db_link;
8 EXECUTE IMMEDIATE v_sql INTO v_test;
9 DBMS_OUTPUT.PUT_LINE(v_test);
10 END;
11 /
Procedure created.
APPS#tst> commit;
Commit complete.
APPS#tst>
APPS#tst>
APPS#tst>
APPS#tst> begin
2 test_dblink('db003link');
3 end;
4 /
X
PL/SQL procedure successfully completed.
This does not have error handling and it assumes one record will be returned (typically not a good assumption).

Related

Stored procedure that creates #table - unable to find it in list of tables

I'm trying to run a stored procedure that creates a local table - #table1
The stored procedure is supposed to look for values and create the table and insert the values into it...
INSERT INTO #table1
I execute the stored procedure and it shows that 1 row() affected, however, I am unable to find this table in the list of my tables. Why am I not able to see it or access it?
EDIT: I'm running the stored procedure inside SQL Server against a database. At the end of the stored procedure, the last line is:
Select * from #table1
Thanks.
The #table is a local temp table. It does not exist as a permanent table that you can look for outside the scope of the stored proc. Once the stored proc is run, the temp table is dropped because it is no longer in scope. Temp tables are stored temporarily in the tempdb database but with a different name because two people running the stored procedure at the same time would each have a table that can be referenced in the proc as #table but it would be two separate tables in the tempdb.
Now if what you are doing is looking to see what is in #table at a point in the stored proc in order to troubleshoot the proc, then you need to set thing up in the proc so that you can see the results at different stages or when you hit a certain state such as an error.
This could be something like adding a #debug variable to the proc so that when you are in debug mode, you can select the results to the screen when you are running something like:
CREATE PROC test_proc (#Id INT, #debug BIT = 0)
AS
CREATE TABLE #temp(id INT)
INSERT INTO #temp
VALUES (#Id), (1), (2)
IF #debug = 1
BEGIN
SELECT * FROM #temp
END
UPDATE #temp
SET Id = id-1
IF #debug = 1
BEGIN
SELECT * FROM #temp
END
GO
You would then execute the proc without debugging as so (note that since I am not returning something or inserting to permanent tables, this proc will insert to #temp but you can't see anything. I just didn't want to get complicated here, the steps of the proc will vary depending on what you want to do, the concept I am trying to show is how to use the debug variable):
EXEC test_proc #Id= 5
and with debugging as
EXEC test_proc #Id= 5, #debug= 1
Or it might involved using a table variable instead (because they don't get rolled back on error) and then inserting the data from that table variable into a logging table after the rollback occurs in the Catch block, so that you can see the values at the time the error occurred.
Without knowing more about why you are looking for #temp and what the data means and is used for, it is hard to say what you need to do.
Did you tried refreshing the tables after exceuting Stored procedure

How one stored procedure can read first recordset from another's execution results?

I need to call stored procedure Foo from another stored procedure Bar. The thing is that Foo returns 2 recordsets and in Bar I want to analyze only the first one.
I've found many advice on how to deal with a single recordset as a callee stored procedure result. But nothing about multiple.
This cannot be done in pure transact SQL, only if you create a CLR-stored procedure (AKA, sp written in .NET)
If you have access to Foo - you can add a parameter to it, to tell which result-set to return.
Something like this pseudo-code:
ALTER Procedure dbo.Foo
(
#ResultSetIndicator smallint = 0
)
AS
BEGIN
if (#ResultSetIndicator = 0)
BEGIN
SELECT xxx
END
if (#ResultSetIndicator = 1)
BEGIN
SELECT yyy
END
END

Create user through procedure on another database via database link

I'd like to create users through procedure on another database via database link.I am getting error while executing procedure.
Here are the code which i used.
create or REPLACE PROCEDURE hostname
(host_name in varchar2,user_name in VARCHAR2, pass_word in VARCHAR2,
table_space in varchar2,pro_file in varchar2)
as
db_link_name varchar2(30);
begin
select db_link into db_link_name from all_db_links where host=host_name;
EXECUTE IMMEDIATE 'dbms_utility.exec_ddl_statement#'||db_link_name||('CREATE USER '||user_name||' IDENTIFIED BY '||pass_word||'
DEFAULT TABLESPACE '||table_space||' PROFILE '|| pro_file||' ACCOUNT UNLOCK');
EXECUTE IMMEDIATE 'dbms_utility.exec_ddl_statement#'||db_link_name||
('GRANT CONNECT,RESOURCE,EXECUTE_CATALOG_ROLE,Create table,create session,create view,create sequence,create procedure,create job,create synonym TO '||user_name);
end;
/
execute hostname('orcl1','rahul1','rahul','users','default');
Error: ORA-00900: invalid SQL statement ORA-06512: at
"SYS.HOSTNAME", line 6 ORA-06512: at line 1
00900. 00000 - "invalid SQL statement"
*Cause:
*Action:
I think you may have got a little confused by some of the advice provided by the commenter mustaccio. What he meant to say is that the SQL strings in your EXECUTE IMMEDIATE statements need to use PL/SQL blocks in order to call stored procedures.
In other words, instead of writing
EXECUTE IMMEDIATE 'dbms_utility.exec_ddl_statement ... ';
you should write
EXECUTE IMMEDIATE 'BEGIN dbms_utility.exec_ddl_statement ... ; END;';
For your procedure, I would recommend doing introducing a local variable for the strings you are passing to EXECUTE IMMEDIATE. These can be notoriously tricky to get right, and if you've assigned them to a local variable you can easily output them using dbms_output.put_line. In fact, I did exactly this while fixing up the problems in your procedure. I would recommend continuing to do this if you wish to modify or extend your procedure.
Anyway, here's what I ended up with, which appeared to work:
create or REPLACE PROCEDURE hostname
(host_name in varchar2,user_name in VARCHAR2, pass_word in VARCHAR2,
table_space in varchar2,pro_file in varchar2)
as
db_link_name varchar2(30);
l_ddl_sql varchar2(4000);
begin
select db_link into db_link_name from all_db_links where host=host_name;
l_ddl_sql := 'begin dbms_utility.exec_ddl_statement#'||db_link_name||'(''CREATE USER '||user_name||' IDENTIFIED BY '||pass_word||'
DEFAULT TABLESPACE '||table_space||' PROFILE '|| pro_file||' ACCOUNT UNLOCK''); END;';
EXECUTE IMMEDIATE l_ddl_sql;
l_ddl_sql := 'begin dbms_utility.exec_ddl_statement#'||db_link_name||
'(''GRANT CONNECT,RESOURCE,EXECUTE_CATALOG_ROLE,Create table,create session,create view,create sequence,create procedure,create job,create synonym TO '||user_name || '''); END;';
EXECUTE IMMEDIATE l_ddl_sql;
end;
/

Find the return value of a PL/SQL function on remote database

I have one Oracle XXg database running on a remote client and it's not possible to reproduce the environment for tests. Right now, there is one stored procedure that's returning an unexpected value (it's just an integer that should be zero but is returning some other number) and I want to discover which value is that.
I can edit the functions and procedures, but I can't call the function without using a big java application that I cannot debug. Is there any way to log the return value to a text file or some log on the database so I can check it after execution?
If there's not such functionality, what would be the less troublesome workaround?
How about creating a table to log the values?
CREATE TABLE mylog (t TIMESTAMP DEFAULT SYSTIMESTAMP, retval NUMBER);
CREATE OR REPLACE PROCEDURE yourprocedure
AS
myval NUMBER;
PROCEDURE logval (myval NUMBER) AS PRAGMA autonomous_transaction;
BEGIN
INSERT INTO mylog(retval) VALUES (myval);
COMMIT;
END logval;
BEGIN
-- your normal code
myval := 1;
-- log the result
logval(myval);
END yourprocedure;
/
Then you can simply select the values from the table mylog...

Errors: "INSERT EXEC statement cannot be nested." and "Cannot use the ROLLBACK statement within an INSERT-EXEC statement." How to solve this?

I have three stored procedures Sp1, Sp2 and Sp3.
The first one (Sp1) will execute the second one (Sp2) and save returned data into #tempTB1 and the second one will execute the third one (Sp3) and save data into #tempTB2.
If I execute the Sp2 it will work and it will return me all my data from the Sp3, but the problem is in the Sp1, when I execute it it will display this error:
INSERT EXEC statement cannot be nested
I tried to change the place of execute Sp2 and it display me another error:
Cannot use the ROLLBACK statement
within an INSERT-EXEC statement.
This is a common issue when attempting to 'bubble' up data from a chain of stored procedures. A restriction in SQL Server is you can only have one INSERT-EXEC active at a time. I recommend looking at How to Share Data Between Stored Procedures which is a very thorough article on patterns to work around this type of problem.
For example a work around could be to turn Sp3 into a Table-valued function.
This is the only "simple" way to do this in SQL Server without some giant convoluted created function or executed sql string call, both of which are terrible solutions:
create a temp table
openrowset your stored procedure data into it
EXAMPLE:
INSERT INTO #YOUR_TEMP_TABLE
SELECT * FROM OPENROWSET ('SQLOLEDB','Server=(local);TRUSTED_CONNECTION=YES;','set fmtonly off EXEC [ServerName].dbo.[StoredProcedureName] 1,2,3')
Note: You MUST use 'set fmtonly off', AND you CANNOT add dynamic sql to this either inside the openrowset call, either for the string containing your stored procedure parameters or for the table name. Thats why you have to use a temp table rather than table variables, which would have been better, as it out performs temp table in most cases.
OK, encouraged by jimhark here is an example of the old single hash table approach: -
CREATE PROCEDURE SP3 as
BEGIN
SELECT 1, 'Data1'
UNION ALL
SELECT 2, 'Data2'
END
go
CREATE PROCEDURE SP2 as
BEGIN
if exists (select * from tempdb.dbo.sysobjects o where o.xtype in ('U') and o.id = object_id(N'tempdb..#tmp1'))
INSERT INTO #tmp1
EXEC SP3
else
EXEC SP3
END
go
CREATE PROCEDURE SP1 as
BEGIN
EXEC SP2
END
GO
/*
--I want some data back from SP3
-- Just run the SP1
EXEC SP1
*/
/*
--I want some data back from SP3 into a table to do something useful
--Try run this - get an error - can't nest Execs
if exists (select * from tempdb.dbo.sysobjects o where o.xtype in ('U') and o.id = object_id(N'tempdb..#tmp1'))
DROP TABLE #tmp1
CREATE TABLE #tmp1 (ID INT, Data VARCHAR(20))
INSERT INTO #tmp1
EXEC SP1
*/
/*
--I want some data back from SP3 into a table to do something useful
--However, if we run this single hash temp table it is in scope anyway so
--no need for the exec insert
if exists (select * from tempdb.dbo.sysobjects o where o.xtype in ('U') and o.id = object_id(N'tempdb..#tmp1'))
DROP TABLE #tmp1
CREATE TABLE #tmp1 (ID INT, Data VARCHAR(20))
EXEC SP1
SELECT * FROM #tmp1
*/
My work around for this problem has always been to use the principle that single hash temp tables are in scope to any called procs. So, I have an option switch in the proc parameters (default set to off). If this is switched on, the called proc will insert the results into the temp table created in the calling proc. I think in the past I have taken it a step further and put some code in the called proc to check if the single hash table exists in scope, if it does then insert the code, otherwise return the result set. Seems to work well - best way of passing large data sets between procs.
This trick works for me.
You don't have this problem on remote server, because on remote server, the last insert command waits for the result of previous command to execute. It's not the case on same server.
Profit that situation for a workaround.
If you have the right permission to create a Linked Server, do it.
Create the same server as linked server.
in SSMS, log into your server
go to "Server Object
Right Click on "Linked Servers", then "New Linked Server"
on the dialog, give any name of your linked server : eg: THISSERVER
server type is "Other data source"
Provider : Microsoft OLE DB Provider for SQL server
Data source: your IP, it can be also just a dot (.), because it's localhost
Go to the tab "Security" and choose the 3rd one "Be made using the login's current security context"
You can edit the server options (3rd tab) if you want
Press OK, your linked server is created
now your Sql command in the SP1 is
insert into #myTempTable
exec THISSERVER.MY_DATABASE_NAME.MY_SCHEMA.SP2
Believe me, it works even you have dynamic insert in SP2
I found a work around is to convert one of the prods into a table valued function. I realize that is not always possible, and introduces its own limitations. However, I have been able to always find at least one of the procedures a good candidate for this. I like this solution, because it doesn't introduce any "hacks" to the solution.
I encountered this issue when trying to import the results of a Stored Proc into a temp table, and that Stored Proc inserted into a temp table as part of its own operation. The issue being that SQL Server does not allow the same process to write to two different temp tables at the same time.
The accepted OPENROWSET answer works fine, but I needed to avoid using any Dynamic SQL or an external OLE provider in my process, so I went a different route.
One easy workaround I found was to change the temporary table in my stored procedure to a table variable. It works exactly the same as it did with a temp table, but no longer conflicts with my other temp table insert.
Just to head off the comment I know that a few of you are about to write, warning me off Table Variables as performance killers... All I can say to you is that in 2020 it pays dividends not to be afraid of Table Variables. If this was 2008 and my Database was hosted on a server with 16GB RAM and running off 5400RPM HDDs, I might agree with you. But it's 2020 and I have an SSD array as my primary storage and hundreds of gigs of RAM. I could load my entire company's database to a table variable and still have plenty of RAM to spare.
Table Variables are back on the menu!
I recommend to read this entire article. Below is the most relevant section of that article that addresses your question:
Rollback and Error Handling is Difficult
In my articles on Error and Transaction Handling in SQL Server, I suggest that you should always have an error handler like
BEGIN CATCH
IF ##trancount > 0 ROLLBACK TRANSACTION
EXEC error_handler_sp
RETURN 55555
END CATCH
The idea is that even if you do not start a transaction in the procedure, you should always include a ROLLBACK, because if you were not able to fulfil your contract, the transaction is not valid.
Unfortunately, this does not work well with INSERT-EXEC. If the called procedure executes a ROLLBACK statement, this happens:
Msg 3915, Level 16, State 0, Procedure SalesByStore, Line 9 Cannot use the ROLLBACK statement within an INSERT-EXEC statement.
The execution of the stored procedure is aborted. If there is no CATCH handler anywhere, the entire batch is aborted, and the transaction is rolled back. If the INSERT-EXEC is inside TRY-CATCH, that CATCH handler will fire, but the transaction is doomed, that is, you must roll it back. The net effect is that the rollback is achieved as requested, but the original error message that triggered the rollback is lost. That may seem like a small thing, but it makes troubleshooting much more difficult, because when you see this error, all you know is that something went wrong, but you don't know what.
I had the same issue and concern over duplicate code in two or more sprocs. I ended up adding an additional attribute for "mode". This allowed common code to exist inside one sproc and the mode directed flow and result set of the sproc.
what about just store the output to the static table ? Like
-- SubProcedure: subProcedureName
---------------------------------
-- Save the value
DELETE lastValue_subProcedureName
INSERT INTO lastValue_subProcedureName (Value)
SELECT #Value
-- Return the value
SELECT #Value
-- Procedure
--------------------------------------------
-- get last value of subProcedureName
SELECT Value FROM lastValue_subProcedureName
its not ideal, but its so simple and you don't need to rewrite everything.
UPDATE:
the previous solution does not work well with parallel queries (async and multiuser accessing) therefore now Iam using temp tables
-- A local temporary table created in a stored procedure is dropped automatically when the stored procedure is finished.
-- The table can be referenced by any nested stored procedures executed by the stored procedure that created the table.
-- The table cannot be referenced by the process that called the stored procedure that created the table.
IF OBJECT_ID('tempdb..#lastValue_spGetData') IS NULL
CREATE TABLE #lastValue_spGetData (Value INT)
-- trigger stored procedure with special silent parameter
EXEC dbo.spGetData 1 --silent mode parameter
nested spGetData stored procedure content
-- Save the output if temporary table exists.
IF OBJECT_ID('tempdb..#lastValue_spGetData') IS NOT NULL
BEGIN
DELETE #lastValue_spGetData
INSERT INTO #lastValue_spGetData(Value)
SELECT Col1 FROM dbo.Table1
END
-- stored procedure return
IF #silentMode = 0
SELECT Col1 FROM dbo.Table1
Declare an output cursor variable to the inner sp :
#c CURSOR VARYING OUTPUT
Then declare a cursor c to the select you want to return.
Then open the cursor.
Then set the reference:
DECLARE c CURSOR LOCAL FAST_FORWARD READ_ONLY FOR
SELECT ...
OPEN c
SET #c = c
DO NOT close or reallocate.
Now call the inner sp from the outer one supplying a cursor parameter like:
exec sp_abc a,b,c,, #cOUT OUTPUT
Once the inner sp executes, your #cOUT is ready to fetch. Loop and then close and deallocate.
If you are able to use other associated technologies such as C#, I suggest using the built in SQL command with Transaction parameter.
var sqlCommand = new SqlCommand(commandText, null, transaction);
I've created a simple Console App that demonstrates this ability which can be found here:
https://github.com/hecked12/SQL-Transaction-Using-C-Sharp
In short, C# allows you to overcome this limitation where you can inspect the output of each stored procedure and use that output however you like, for example you can feed it to another stored procedure. If the output is ok, you can commit the transaction, otherwise, you can revert the changes using rollback.
On SQL Server 2008 R2, I had a mismatch in table columns that caused the Rollback error. It went away when I fixed my sqlcmd table variable populated by the insert-exec statement to match that returned by the stored proc. It was missing org_code. In a windows cmd file, it loads result of stored procedure and selects it.
set SQLTXT= declare #resets as table (org_id nvarchar(9), org_code char(4), ^
tin(char9), old_strt_dt char(10), strt_dt char(10)); ^
insert #resets exec rsp_reset; ^
select * from #resets;
sqlcmd -U user -P pass -d database -S server -Q "%SQLTXT%" -o "OrgReport.txt"

Resources