I have about 15 databases with the same tables that I need to run the same query on and combine. I usually copy and paste the query and rename the database each time but this isn't scalable and I may need to add additional databases in the future.
To avoid having to go and add each one, is there a way I can essentially loop through a table I create with the database name and a few flags and run the query for any database with the correct flags?
How does CSV generation affect SQL performance on SQL Server?
I want to generate CSV files from an active production database. These tables have 10-20-30 million rows stored in them. These are not particularly wide tables, but they are used actively.
Approach would be like: create copies of tables with "SELECT * INTO [newTable] FROM..." - I think it should copy data fast into another table. Export file from copytable, so production table would not get locked unintentionally. I'm not sure if this step is actually necessary, or if it helps anything.
Thanks!
I am trying to migrate data from table A of database DB1 to table B of database DB2 using java and Oracle.
I am using java 1.8 and my source database has Oracle 11g and destination database has Oracle 12c.
I made structure (scema, tables )of destination database in source database. And migrating as by making use of *insert into dest select * from source* query in java . but as the number of records in source table in millions so it's consuming time.. and later on this migrated data i want to export into my actual destination so that too will going to take time.
As per my little knowledge.. i think I can't use prepared statement with 2 connection. Because my table consists of 400 to 500 columns , so binding that many columns with prepared statement is not a good idea. Also my structure of source and destination tables are different. I made the field mapping in properties file where I mapped the old field to new field for insert into select * from tbl query. Like my source table has column as col0001 and the corresponding column in destination is ref_no. So this too will not allow me to use prepared statement. But by making use of statement in java i can migrate data in single dB only.
I tried with dblink also. But for clob datatype i am not able to migrate data.
Kindly provide the solution if anyone did something like this previously.
For a one-off copy, you can do a direct mode insert:
insert /*+ APPEND */ into local_table select * from table#database_link;
Here are some other related links.
How can I sync two databases and do a manual refresh on the entities on either of the database whenever I want?
Let's say I have two databases DB1(prod) and DB2(dev). I want to update/insert only a few tables from prod DB to dev DB. How could I achieve this? Is this possible instead of DBlink since I do not have privileges to create a database link?
If you only want to do a manual refresh set up an import/export/datapump script to copy the data across if there is not too much data involved. If there is a large amount of data you could write some pl/sql as described above to only move the new/changed rows. This will be easier if your data has fields such as created/updated_on
I have to copy the tables with data from one database to another using Query. I know how to copy tables with data within a database. But I was not sure about how to do the same for copying between two databases.
I have to copy huge number of tables, so I need any fast method using query...
Anybody please help out...Thanks in advance...
You can use the same way to copy the tables within one database, the SELECT INTO but use a fully qualified tables names database.schema.object_name instead like so:
USE TheOtherDB;
SELECT *
INTO NewTable
FROM TheFirstDB.Schemaname.OldTable
This will create a new table Newtable in the database TheOtherDB from the table OldTable whih belongs to the databaseTheFirstDB
Right click on the database, select tasks and click on Generate Scripts.
In the resultant pop-up, choose options as required (click advanced), to drop and create table, drop if exists, etc.
Scroll down and choose "Schema and Data" or "Data Only" or "Types of data to script (2008 R2)"as required.
Save to file and execute on the destination DB.
Advantages -
Can be executed against the destination DB, even if it is on another server / instance
Quickly script multiple tables, with data as needed
Warning - Might take quite a while to script, if the tables contain a large amount of data.
Rajan
INSERT INTO DB2.dbo.MyOtherTable (Col0, Col1)
SELECT Col0, Col1 FROM DB1.dbo.MyTable
Both table column's must have same data types..
Below SQL Query will copy SQL Server table schema & data from one database to another database. You can always table name (SampleTable) in your destination database.
SELECT * INTO DestinationDB.dbo.SampleTable FROM SourceDB.dbo.SampleTable