I have a particular SQL file in which i copy all contents from on table in a database to another table in another database.
The traditional INSERT statements are used to perform the same operation. However this table has 8.5 Million records and it fails. The queries succeed with a smaller database.
Also in when i run the select * query for that particular table the SQL query express shows out of memory exception.
In particular there is one table that has some many records. So this table alone i want to copy from the old Db to the new Db.
What are alternate ways to achieve this?
Is there any quick work around by which we can avoid this exception and make the queries succeed?
Let me put it this way. Why would this operation fail when there are a lot of records?
I don't know if this counts as "traditional INSERT", but have you tried "INSERT INTO"?
http://www.w3schools.com/sql/sql_select_into.asp
Related
I have a set of 10 tables in a database (DB1). And there are 10 tables in another database (DB2) with exact same schema on the same SQL Server 2008 R2 database server machine.
The 10 tables in DB1 are frequently updated with data.
I intend to write a stored procedure that would run once every day for synchronizing the 10 tables in DB1 with DB2. The stored procedure would make use of the MERGE statement.
Now, my aim is to make this as generic and parametrized as possible. That is, accommodate for more tables down the line... and accommodate different source and target DB names. Definitely no hard coding is intended.
This is my algorithm so far:
Have the database names as parameters
Have the first query within the stored procedure... result in giving the names of the 10 tables from a lookup table (this can be 10, 20 or whatever)
Have a generic MERGE statement that does the sync for each of the above set of tables (based on primary key?)
This is where I need more inputs on.
What is the best way to achieve this stored procedure? SQL syntax would be helpful.
I had to do something similar, to do that i used a string with a "skeleton" for the merge statement, then i retrieved the list of columns and the pks with a simple query on the sys views.
you could do something similar to build your merge statement, here's a sketch i wrote now as an example (I know it's horrible but i'm not going to write something decent at this hour, and it should give you a hint anyway :P )
SQLFiddle
then you just need to execute it with the usual sp_executesql stored procedure
by the way, always pay attention when building command strings this way, it's not that secure
How do I debug a complex query with multiple nested sub-queries in SQL Server 2005?
I'm debugging a stored procedure and trigger in Visual Studio 2005. I'd like to be able to see what the results of these sub-queries are, as I feel that this is where the bug is coming from. An example query (slightly redacted) is below:
UPDATE
foo
SET
DateUpdated = ( SELECT TOP 1 inserted.DateUpdated FROM inserted )
...
FROM
tblEP ep
JOIN tblED ed ON ep.EnrollmentID = ed.EnrollmentID
WHERE
ProgramPhaseID = ( SELECT ...)
Visual Studio doesn't seem to offer a way for me to Watch the result of the sub query. Also, if I use a temporary table to store the results (temporary tables are used elsewhere also) I can't view the values stored in that table.
Is there anyway that I can add a watch or in some other way view these sub-queries? I would love it if there was some way to "Step Into" the query itself, but I imagine that wouldn't be possible.
Ok first I would be leary of using subqueries in a trigger. Triggers should be as fast as possible, so get rid of any correlated subqueries which might run row by row instead of in a set-based fashion. Rewrite to joins. If you only want to update records based on what was in the inserted table, then join to it. Also join to the table you are updating. Exactly what are you trying to accomplish with this trigger? It might be easier to give advice if we understood the business rule you are trying to implement.
To debug a trigger this is what I do.
I write a script to:
Do the actual insert to the table
without the trigger on on it
Create a temp table named #inserted
(and/or one named #deleted)
Populate the table as I would expect
the inserted table in the trigger to
be populated from the insert you do.
Add the trigger code (minus the
create or alter trigger parts)
substituting #inserted every time I
reference inserted. (if you plan to
run multiple times until you are
ready to use it in a trigger throw
it in an explicit transaction and
rollback after checking your
results.
Add a query to check the table(s)
you are changing with the trigger for
the values you wanted to change.
Now if you need to add debug
statements to see what is happening
between steps, you can do so.
Run making changes until you get the
results you want.
Once you have the query working as
you expect it to, it is easy to take
the # signs off inserted and use it
to create the body of the trigger.
This is what I usually do in this type of scenerio:
Print out the exact sqls getting generated by each subquery
Then run each of then in the Management Studio as suggested above.
You should check if different parts are giving you the right data you expect.
I ran a large query (~30mb) which inserts data in ~20 tables. Accidentally, I selected wrong database. There are only 2 tables with same name but with different columns. Now I want to make sure that no data is inserted in this database, I just don't know how.
If your table has a timestamp you can test for that.
Also sql-server keeps a log of all transactions.
See: https://web.archive.org/web/20080215075500/http://sqlserver2000.databases.aspfaq.com/how-do-i-recover-data-from-sql-server-s-log-files.html
This will show you how to examine the log to see if any inserts happened.
Best option go for Trigger
Use trigger to find the db name and
table name and all the history of
records manipulated
I am working on an in-house ETL solution, from db1 (Oracle) to db2 (Sybase). We needs to transfer data incrementally (Change Data Capture?) into db2.
I have only read access to tables, so I can't create any table or trigger in Oracle db1.
The challenge I am facing is, how to detect record deletion in Oracle?
The solution which I can think of, is by using additional standalone/embedded db (e.g. derby, h2 etc). This db contains 2 tables, namely old_data, new_data.
old_data contains primary key field from tahle of interest in Oracle.
Every time ETL process runs, new_data table will be populated with primary key field from Oracle table. After that, I will run the following sql command to get the deleted rows:
SELECT old_data.id FROM old_data WHERE old_data.id NOT IN (SELECT new_data.id FROM new_data)
I think this will be a very expensive operation when the volume of data become very large. Do you have any better idea of doing this?
Thanks.
Which edition of Oracle ? If you have Enterprise Edition, look into Oracle Streams.
You can grab the deletes out of the REDO log rather than the database itself
One approach you could take is using the Oracle flashback capability (if you're using version 9i or later):
http://forums.oracle.com/forums/thread.jspa?messageID=2608773
This will allow you to select from a prior database state.
If there may not always be deleted records, you could be more efficient by:
Storing a row count with each query iteration.
Comparing that row count to the previous row count.
If they are different, you know you have a delete and you have to compare the current set with the historical data set from flashback. If not, then don't bother and you've saved a lot of cycles.
A quick note on your solution if flashback isn't an option: I don't think your select query is a big deal - it's all those inserts to populate those side tables that will really take a lot of time. Why not just run that query against the sybase production server before doing your update?
One third party app is storing data in a huge database (SQL Server 2000/2005). This database has more than 80 tables. How would I come to know that how many tables are affected when application stores a new record in database? Is there something available I can retrieve the list of tables affected?
You might be able to tell by running a trace in SQL Profiler on the database - the SQL:StmtCompleted event is probably the one to monitor - i.e. if the application does a series of inserts into multiple tables, you should see them go through in Profiler.
You can use SQL Profiler to trace SQL queries. So you will see sequence of calls caused by one button click in your application.
Also use can use metadata or SQL tools to get list of triggers which could make a lot of actions on simple insert.
If you have the SQL script that used to store the new record(Usually, it should be insert statement, or other DML statement such as update, merge and so on). Then you may know how many tables were affected by parsing those SQL script.
Take this SQL for example:
Insert into emp(fname, lname)
Values('john', 'reyes')
You can get result like this:
sstinsert
emp(tetInsert)
Tables:
emp
Fields:
emp.fname
emp.lname
you can add triggers on tables that get fired on update - you could use this to update a log table that would report what was being updated.
see more here: http://www.devarticles.com/c/a/SQL-Server/Using-Triggers-In-MS-SQL-Server/
Profiler is the way to go, as others have said especially with an unfamilar third party database.
I would also spend some time creating diagrams so you can see the foreign key relationships and understand how the database is put together. I usaully know my database structure so well, I can tell from the fields being inserted what tables they affect and I know what triggers are on my tables and what they affect. There is no substitute for taking the time to understand the database you support.