Let say, I am connected to two different databases (one SQLite and one Oracle) over ODBC in one program. Is it possible to execute a query on one database and insert the resultset as a new table in the second database directly by just passing something like a data cursor, i.e. without the hurdle to create insert statements with explicit values from the result set and executing those on the destination database?
As far as I am aware you cannot do that. You can use something like a join engine to do it (e.g., http://www.easysoft.com/products/data_access/odbc_odbc_join_engine/index.html) but it might be overkill if you are doing it just the once.
If you use Oracle then you can use Oracle Heterogeneous Services which can work with ODBC sources. Have a look at: http://www.dba-oracle.com/t_heterogeneous_database_connections_sql_server.htm
Related
After trying a few different packages and methods found online, I am yet to find a solution that works for inserting a dataframe from R into an existing table in SQL Server.
I've had great success doing this with MySQL, but SQL Server seems to be more difficult.
I have managed to write a new table using the DBI package, but I can't find a way to insert into using this method. Looking at the documentation, there doesn't seem to be a way of inserting.
As there are more than 1000 rows of data, using sqlQuery from the RODBC package also seems unfeasable.
Can anybody suggest a working method for inserting large amounts of data from a dataframe into an existing SQL table?
I've had similar needs using R and PostGreSQL using the r-postgres-specific drivers. I imagine similar issues may exist with SQLServer. The best solution I found was to write to a temporary table in the database using either dbWriteTable or one of the underlying functions to write from a stream to load very large tables (for Postgres, postgresqlCopyInDataframe, for example). The latter usually requires more work in terms of defining and aligning SQL data types and R class types to ensure writing, wheres dbWriteTable tends to be a bit easier. Once written to a temporary table, to then issue an SQL statement to insert into your table as you would within the database environment. Below is an example using high-level DBI library database calls:
dbExecute(conn,"start transaction;")
dbExecute(conn,"drop table if exists myTempTable")
dbWriteTable(conn,"myTempTable",df)
dbExecute(conn,"insert into myRealTable(a,b,c) select a,b,c from myTempTable")
dbExecute(conn,"drop table if exists myTempTable")
dbExecute(conn,"commit;")
We are migrating database structures, so I have one database with the old structure and one database with the new structure (both on the same server). I want to write queries to copy data from one to the other. I am expecting to go table-by-table as the schema is different. How do I do this?
You need to provide more details to get a more specific answer, but in general you just use the three-part name:
INSERT INTO NewDB.dbo.TableName
SELECT <columns>
FROM OldDB.dbo.Tablename
Are you looking for a way to do this automatically for all the tables?
You can write cross database queries like so
INSERT INTO NewDatabase.Schema.Table
SELECT Column1, Column2
FROM OldDatabase.Schema.Table
you can probably use Import data under tasks.Right Click the Target DB -> Tasks ->Import Data .You can also specify the source-> target mapping here.. and also write queries
I have two instances of same database and I want to have only one instance of database, so what I need is to import data from one databes to another.
Ofc I can go table by table, but there is lots of tables. I was wondering is there sql statement that can merge two databases or is there option in Microsoft SQL server database studio to this thing?
There is nothing built in like that.
If you don't want to go the manual way (comparing and then importing/exporting), you can look at a propriety tool like RedGate Data Compare that can accomplish this.
When I right click on the database I want to export data from, I only get to select a single table or view, rather than being able to export all of the data. Is there a way to export all of the data?
If this is not possible, could you advise on how I could do the following:
I have two databases, with the same table names, but one has more data than the other
They both have different database names (Table names are identical)
They are both on different servers
I need to get all of the additional data from the larger database, into the smaller database.
Both are MS SQL databases
Being that both are MS SQL Servers, on different hosts... why bother with CSV when you can setup a Linked Server instance so you can access one instance from the other via a SQL statement?
Make sure you have a valid user on the instance you want to retrieve data from - it must have access to the table(s)
Create the Linked Server instance
Reference the name in queries using four name syntax:
INSERT INTO db1.dbo.SmallerTable
SELECT *
FROM linked_server.db.dbo.LargerTable lt
WHERE NOT EXISTS(SELECT NULL
FROM db1.dbo.SmallerTable st
WHERE st.col = lt.col)
Replace WHERE st.col = lt.col with whatever criteria you consider to be duplicate values between the two tables.
There is also a very good tool by Redgate software that syncs data between two databases.
I've also used SQL scripter before to generate a SQL file with insert statements that you can run on the other database to insert the data.
If you right-click on the database, under the Tasks menu, you can use the Generate Scripts option to produce SQL scripts for all the tables and data. See this blog post for details. If you want to sync the second database with the first, then you're better off using something like Redgate as suggested in mpenrow's answer.
I would like to copy parts of an Oracle DB to a SQL Server DB. I need to move the data because the Oracle box is being decommissioned. I only need the data for reference purposes so don't need indexes or stored procedures or contstaints, etc. All I need is the data.
I have a link to the Oracle DB in SQL Server. I have tested the following query, which seemed to work just fine:
select
*
into
NewTableName
from
linkedserver.OracleTable
I was wondering if there are any potential issues with using this approach?
Using SSIS (sql integration services) may be a good alternative especially if your table names are the same on both servers. Use the import wizard via and it should create the destination tables for you and let you edit any mappings.
The only issue I see with that is you will need to execute that of course for each and every table you need. Glad you are decommissioning the oracle server :-). Otherwise if you are not concerned with indexes or any of the existing sprocs I don't see any issue in what you are doing.
The "select " approach could be very slow if tables are large. Consider writing pro*C in that case or use Fastreader http://www.wisdomforce.com/products-FastReader.html
A faster and easier approach might be to use the Data Transformation Services, depending on the number of objects you're trying to copy over.