We have two databases let say 'D1' and 'D2'. There is one table in each database, say T1 in D1 and T2 in D2.
Now I want to write a store procedure in database D1 which will access table in database D2 something like below code...
USE D1
GO
Create or replace sp_test
(
--other detials
SELECT * FROM D2.dbo.T2
)
GO
Any idea how can I do this?
Note: Earlier we used to have both the databases on to same server. So I didn't face any problem. But now after migrating to Azure I don't have any idea how we can do this. Also as per my information we don't have linked server feature available in SQL-Azure.
Azure SQL Database (or SQL Azure) don't support cross-database queries, so there's no work around other than getting rid of those cross-database queries...
If you are in SQL Azure V12 and your server has a few databases with same edition and you are not permanently depend on cross database transactions(I meant just for a few things, please note that not for cross database queries, this you still need to do at application level), you may want to use sp_bindsession. If you are lucky enough you may end up both databases on the same server. The recommendation is not for any application development but one time things.
This is now possible in SQL Azure. Essentially you need to create an external data source in D1 and an eternal table in D1 that matches the target table in D2.
Something like this
USE D1
-- Not sure if the following line is necessary. Omit it and if SQL Squeals, put it in.
CREATE MASTER KEY ENCRYPTION BY PASSWORD='MasterKeyPassword';
CREATE DATABASE SCOPED CREDENTIAL D2User WITH IDENTITY='D2UserID', SECRET='D2UserPassword';
CREATE EXTERNAL DATA SOURCE D2DataSource
WITH
(
TYPE=RDBMS,
LOCATION='d2.database.windows.net',
DATABASE_NAME='D2',
CREDENTIAL=D2User
);
CREATE EXTERNAL TABLE [dbo].[T2](
[ID] [INT] NOT NULL,
[Info] [NVARCHAR] (25) NULL
)
WITH
(
DATA_SOURCE = D2DataSource
);
Of course you have to replace all the relevant details with your own chosen passwords, database locations etc.
Related
I'm going to guess that the answer is "no" based on the below error message (and this Google result), but is there anyway to perform a cross-database query using PostgreSQL?
databaseA=# select * from databaseB.public.someTableName;
ERROR: cross-database references are not implemented:
"databaseB.public.someTableName"
I'm working with some data that is partitioned across two databases although data is really shared between the two (userid columns in one database come from the users table in the other database). I have no idea why these are two separate databases instead of schema, but c'est la vie...
Note: As the original asker implied, if you are setting up two databases on the same machine you probably want to make two schemas instead - in that case you don't need anything special to query across them.
postgres_fdw
Use postgres_fdw (foreign data wrapper) to connect to tables in any Postgres database - local or remote.
Note that there are foreign data wrappers for other popular data sources. At this time, only postgres_fdw and file_fdw are part of the official Postgres distribution.
For Postgres versions before 9.3
Versions this old are no longer supported, but if you need to do this in a pre-2013 Postgres installation, there is a function called dblink.
I've never used it, but it is maintained and distributed with the rest of PostgreSQL. If you're using the version of PostgreSQL that came with your Linux distro, you might need to install a package called postgresql-contrib.
dblink() -- executes a query in a remote database
dblink executes a query (usually a SELECT, but it can be any SQL
statement that returns rows) in a remote database.
When two text arguments are given, the first one is first looked up as
a persistent connection's name; if found, the command is executed on
that connection. If not found, the first argument is treated as a
connection info string as for dblink_connect, and the indicated
connection is made just for the duration of this command.
one of the good example:
SELECT *
FROM table1 tb1
LEFT JOIN (
SELECT *
FROM dblink('dbname=db2','SELECT id, code FROM table2')
AS tb2(id int, code text);
) AS tb2 ON tb2.column = tb1.column;
Note: I am giving this information for future reference. Reference
I have run into this before an came to the same conclusion about cross database queries as you. What I ended up doing was using schemas to divide the table space that way I could keep the tables grouped but still query them all.
Just to add a bit more information.
There is no way to query a database other than the current one. Because PostgreSQL loads database-specific system catalogs, it is uncertain how a cross-database query should even behave.
contrib/dblink allows cross-database queries using function calls. Of course, a client can also make simultaneous connections to different databases and merge the results on the client side.
PostgreSQL FAQ
Yes, you can by using DBlink (postgresql only) and DBI-Link (allows foreign cross database queriers) and TDS_LInk which allows queries to be run against MS SQL server.
I have used DB-Link and TDS-link before with great success.
I have checked and tried to create a foreign key relationships between 2 tables in 2 different databases using both dblink and postgres_fdw but with no result.
Having read the other peoples feedback on this, for example here and here and in some other sources it looks like there is no way to do that currently:
The dblink and postgres_fdw indeed enable one to connect to and query tables in other databases, which is not possible with the standard Postgres, but they do not allow to establish foreign key relationships between tables in different databases.
If performance is important and most queries are read-only, I would suggest to replicate data over to another database. While this seems like unneeded duplication of data, it might help if indexes are required.
This can be done with simple on insert triggers which in turn call dblink to update another copy. There are also full-blown replication options (like Slony) but that's off-topic.
see https://www.cybertec-postgresql.com/en/joining-data-from-multiple-postgres-databases/ [published 2017]
These days you also have the option to use https://prestodb.io/
You can run SQL on that PrestoDB node and it will distribute the SQL query as required. It can connect to the same node twice for different databases, or it might be connecting to different nodes on different hosts.
It does not support:
DELETE
ALTER TABLE
CREATE TABLE (CREATE TABLE AS is supported)
GRANT
REVOKE
SHOW GRANTS
SHOW ROLES
SHOW ROLE GRANTS
So you should only use it for SELECT and JOIN needs. Connect directly to each database for the above needs. (It looks like you can also INSERT or UPDATE which is nice)
Client applications connect to PrestoDB primarily using JDBC, but other types of connection are possible including a Tableu compatible web API
This is an open source tool governed by the Linux Foundation and Presto Foundation.
The founding members of the Presto Foundation are: Facebook, Uber,
Twitter, and Alibaba.
The current members are: Facebook, Uber, Twitter, Alibaba, Alluxio,
Ahana, Upsolver, and Intel.
In case someone needs a more involved example on how to do cross-database queries, here's an example that cleans up the databasechangeloglock table on every database that has it:
CREATE EXTENSION IF NOT EXISTS dblink;
DO
$$
DECLARE database_name TEXT;
DECLARE conn_template TEXT;
DECLARE conn_string TEXT;
DECLARE table_exists Boolean;
BEGIN
conn_template = 'user=myuser password=mypass dbname=';
FOR database_name IN
SELECT datname FROM pg_database
WHERE datistemplate = false
LOOP
conn_string = conn_template || database_name;
table_exists = (select table_exists_ from dblink(conn_string, '(select Count(*) > 0 from information_schema.tables where table_name = ''databasechangeloglock'')') as (table_exists_ Boolean));
IF table_exists THEN
perform dblink_exec(conn_string, 'delete from databasechangeloglock');
END IF;
END LOOP;
END
$$
I have a database on Azure using the SQL Database (PaaS) offering.
I can't see or access the tempdb nor can I create it.
If I try to create the database I get the following error:
Msg 1801, Level 16, State 3, Line 10
Database 'tempdb' already exists. Choose a different database name.
Does anyone know what's going on here?
TempDB on Azure SQL Database is created and managed by Azure platform and the TempDB capacity has a limit in size based on the Azure SQL Database tier.
Hope this helps.
I am going to up tick Alberto since he is right about the service handling this system database.
I guess my main question is why are you using [tempdb]?
Before there was a push to the cloud, lazy SQL developers would create tables in [tempdb]. These tables should have been placed into a user defined staging database or schema.
Let's see if local/global temporary tables and user defined tables in [tempdb] are allowed.
-- local temp table
select 'Fee Fie Foo Fumb' as rhymes into #a
go
-- show the data
select * from #a
go
-- show my local tables
select * from tempdb.sys.tables
go
The expected results are shown below. Local and global temp tables are supported.
If we try the following create statement within Azure SQL database, the service is smart enough to know that you can not use [tempdb] directly.
Now, back to my first question.
Why are you trying to use and/or modify [tempdb]??
In rebuttal to Alberto, global temporary tables are now supported in Azure. The database being referenced by the session is a Basic tier (b0) level.
This is probably stupid simple, but for some reason I'm having trouble getting it to work. I have a typical import script I'm trying to run on a MS SQL server with one master user (as opposed to a single user with only access to one database).
When I run the .SQL script, it creates the database and then starts to create tables. Here's where it gets interesting. It's not creating the databases under the DB I just made. It's throwing the tables under the "System Databases" view and not restricting the table creation to the DB that was just created.
I have tried:
CREATE TABLE table_name
CREATE TABLE database_name.table_name
Maybe I'm overlooking something really easy. I don't usually run into this with MySQL with a single user mapped to one database, I think since the user can only see that one database, so MySQL assumes it must be the one to work with.
The difference now is that I'm using MSSQL 2008 and maybe it works a little differently and I'm overlooking something. Thanks for your help!
Tried this too. No luck. Says database doesn't exist when it tries to create the table. I would think being a top/down read of the query script it would first create the database, then try to create the table afterwards.
CREATE DATABASE DATABASENAME;
CREATE TABLE DATABASENAME.dbo.TABLENAME
(
field_one VARCHAR(100) NOT NULL,
field_two INT NOT NULL,
PRIMARY KEY(field_one)
)
This is a working example after getting it all figured out. This syntax works well and I don't need to specify the DBO pathing stuff before table names this way. Cleaner and got me the results I was looking for. Thanks everyone.
IF Db_id('DBNAME') IS NULL
CREATE DATABASE DBNAME;
GO
USE [DBNAME];
GO
CREATE TABLE TABLENAME
(
COL1 VARCHAR(100) NOT NULL,
COL2 INT NOT NULL,
PRIMARY KEY(COL2)
)
INSERT INTO TABLENAME
(COL1,
COL2)
VALUES('1234',1001),
('1234',1002),
('1234',1003),
('1234',1004)
It basically just does a check to make sure database is created before doing anything else, then sets the USE database to the one I'm working with. Everything else is just normal SQL, so have fun. Cheers!
Probably you need to include the USE sentence at the begining of your script in order to indicate the database as follows:
USE [database_name]
GO
By default SQL-SERVER use the master DB that´s listed under system databases.
Other way is to use the database prefix, but including the owner:
INSERT INTO database_name.dbo.table_name
INSERT INTO database_name..table_name
I have a database called foo and a database called bar. I have a table in foo called tblFoobar that I want to move (data and all) to database bar from database foo. What is the SQL statement to do this?
SQL Server Management Studio's "Import Data" task (right-click on the DB name, then tasks) will do most of this for you. Run it from the database you want to copy the data into.
If the tables don't exist it will create them for you, but you'll probably have to recreate any indexes and such. If the tables do exist, it will append the new data by default but you can adjust that (edit mappings) so it will delete all existing data.
I use this all the time and it works fairly well.
On SQL Server? and on the same database server? Use three part naming.
INSERT INTO bar..tblFoobar( *fieldlist* )
SELECT *fieldlist* FROM foo..tblFoobar
This just moves the data. If you want to move the table definition (and other attributes such as permissions and indexes), you'll have to do something else.
This should work:
SELECT *
INTO DestinationDB..MyDestinationTable
FROM SourceDB..MySourceTable
It will not copy constraints, defaults or indexes. The table created will not have a clustered index.
Alternatively you could:
INSERT INTO DestinationDB..MyDestinationTable
SELECT * FROM SourceDB..MySourceTable
If your destination table exists and is empty.
If it’s one table only then all you need to do is
Script table definition
Create new table in another database
Update rules, indexes, permissions and such
Import data (several insert into examples are already shown above)
One thing you’ll have to consider is other updates such as migrating other objects in the future. Note that your source and destination tables do not have the same name. This means that you’ll also have to make changes if you dependent objects such as views, stored procedures and other.
Whit one or several objects you can go manually w/o any issues. However, when there are more than just a few updates 3rd party comparison tools come in very handy. Right now I’m using ApexSQL Diff for schema migrations but you can’t go wrong with any other tool out there.
Script the create table in management studio, run that script in bar to create the table. (Right click table in object explorer, script table as, create to...)
INSERT bar.[schema].table SELECT * FROM foo.[schema].table
You can also use the Generate SQL Server Scripts Wizard to help guide the creation of SQL script's that can do the following:
copy the table schema
any constraints (identity, default values, etc)
data within the table
and many other options if needed
Good example workflow for SQL Server 2008 with screen shots shown here.
You may go with this way: ( a general example )
insert into QualityAssuranceDB.dbo.Customers (columnA, ColumnB)
Select columnA, columnB from DeveloperDB.dbo.Customers
Also if you need to generate the column names as well to put in insert clause, use:
select (name + ',') as TableColumns from sys.columns
where object_id = object_id('YourTableName')
Copy the result and paste into query window to represent your table column names and even this will exclude the identity column as well:
select (name + ',') as TableColumns from sys.columns
where object_id = object_id('YourTableName') and is_identity = 0
Remember the script to copy rows will work if the databases belongs to the same location.
You can Try This.
select * into <Destination_table> from <Servername>.<DatabaseName>.dbo.<sourceTable>
Server name is optional if both DB is in same server.
I give you three options:
If they are two databases on the same instance do:
SELECT * INTO My_New_Table FROM [HumanResources].[Department];
If they are two databases on different servers and you have linked servers do:
SELECT * INTO My_New_Table FROM [ServerName].[AdventureWorks2012].[HumanResources].[Department];
If they are two databases on different servers and you don't have linked servers do:
SELECT * INTO My_New_Table
FROM OPENROWSET('SQLNCLI', 'Server=My_Remote_Server;Trusted_Connection=yes;',
'SELECT * FROM AdventureWorks2012.HumanResources.Department');
I'm going to guess that the answer is "no" based on the below error message (and this Google result), but is there anyway to perform a cross-database query using PostgreSQL?
databaseA=# select * from databaseB.public.someTableName;
ERROR: cross-database references are not implemented:
"databaseB.public.someTableName"
I'm working with some data that is partitioned across two databases although data is really shared between the two (userid columns in one database come from the users table in the other database). I have no idea why these are two separate databases instead of schema, but c'est la vie...
Note: As the original asker implied, if you are setting up two databases on the same machine you probably want to make two schemas instead - in that case you don't need anything special to query across them.
postgres_fdw
Use postgres_fdw (foreign data wrapper) to connect to tables in any Postgres database - local or remote.
Note that there are foreign data wrappers for other popular data sources. At this time, only postgres_fdw and file_fdw are part of the official Postgres distribution.
For Postgres versions before 9.3
Versions this old are no longer supported, but if you need to do this in a pre-2013 Postgres installation, there is a function called dblink.
I've never used it, but it is maintained and distributed with the rest of PostgreSQL. If you're using the version of PostgreSQL that came with your Linux distro, you might need to install a package called postgresql-contrib.
dblink() -- executes a query in a remote database
dblink executes a query (usually a SELECT, but it can be any SQL
statement that returns rows) in a remote database.
When two text arguments are given, the first one is first looked up as
a persistent connection's name; if found, the command is executed on
that connection. If not found, the first argument is treated as a
connection info string as for dblink_connect, and the indicated
connection is made just for the duration of this command.
one of the good example:
SELECT *
FROM table1 tb1
LEFT JOIN (
SELECT *
FROM dblink('dbname=db2','SELECT id, code FROM table2')
AS tb2(id int, code text);
) AS tb2 ON tb2.column = tb1.column;
Note: I am giving this information for future reference. Reference
I have run into this before an came to the same conclusion about cross database queries as you. What I ended up doing was using schemas to divide the table space that way I could keep the tables grouped but still query them all.
Just to add a bit more information.
There is no way to query a database other than the current one. Because PostgreSQL loads database-specific system catalogs, it is uncertain how a cross-database query should even behave.
contrib/dblink allows cross-database queries using function calls. Of course, a client can also make simultaneous connections to different databases and merge the results on the client side.
PostgreSQL FAQ
Yes, you can by using DBlink (postgresql only) and DBI-Link (allows foreign cross database queriers) and TDS_LInk which allows queries to be run against MS SQL server.
I have used DB-Link and TDS-link before with great success.
I have checked and tried to create a foreign key relationships between 2 tables in 2 different databases using both dblink and postgres_fdw but with no result.
Having read the other peoples feedback on this, for example here and here and in some other sources it looks like there is no way to do that currently:
The dblink and postgres_fdw indeed enable one to connect to and query tables in other databases, which is not possible with the standard Postgres, but they do not allow to establish foreign key relationships between tables in different databases.
If performance is important and most queries are read-only, I would suggest to replicate data over to another database. While this seems like unneeded duplication of data, it might help if indexes are required.
This can be done with simple on insert triggers which in turn call dblink to update another copy. There are also full-blown replication options (like Slony) but that's off-topic.
see https://www.cybertec-postgresql.com/en/joining-data-from-multiple-postgres-databases/ [published 2017]
These days you also have the option to use https://prestodb.io/
You can run SQL on that PrestoDB node and it will distribute the SQL query as required. It can connect to the same node twice for different databases, or it might be connecting to different nodes on different hosts.
It does not support:
DELETE
ALTER TABLE
CREATE TABLE (CREATE TABLE AS is supported)
GRANT
REVOKE
SHOW GRANTS
SHOW ROLES
SHOW ROLE GRANTS
So you should only use it for SELECT and JOIN needs. Connect directly to each database for the above needs. (It looks like you can also INSERT or UPDATE which is nice)
Client applications connect to PrestoDB primarily using JDBC, but other types of connection are possible including a Tableu compatible web API
This is an open source tool governed by the Linux Foundation and Presto Foundation.
The founding members of the Presto Foundation are: Facebook, Uber,
Twitter, and Alibaba.
The current members are: Facebook, Uber, Twitter, Alibaba, Alluxio,
Ahana, Upsolver, and Intel.
In case someone needs a more involved example on how to do cross-database queries, here's an example that cleans up the databasechangeloglock table on every database that has it:
CREATE EXTENSION IF NOT EXISTS dblink;
DO
$$
DECLARE database_name TEXT;
DECLARE conn_template TEXT;
DECLARE conn_string TEXT;
DECLARE table_exists Boolean;
BEGIN
conn_template = 'user=myuser password=mypass dbname=';
FOR database_name IN
SELECT datname FROM pg_database
WHERE datistemplate = false
LOOP
conn_string = conn_template || database_name;
table_exists = (select table_exists_ from dblink(conn_string, '(select Count(*) > 0 from information_schema.tables where table_name = ''databasechangeloglock'')') as (table_exists_ Boolean));
IF table_exists THEN
perform dblink_exec(conn_string, 'delete from databasechangeloglock');
END IF;
END LOOP;
END
$$