I would like to join fields from two different databases that reside on the same server, but I am having trouble with the syntax.
Can anyone provide some insight?
Assuming that your user has privileges in both databases, just reference the "remote" object using three part naming:
SELECT columns
FROM database2.dbo.table
Related
We have 4 distinct environments for one of our applications through our Dev to Prod pipeline, each having two databases. Within these databases there are several queries referencing the other database. So for example we may have this:
select a.name, b.description
FROM Database1.dbo.Names a
INNER join Database2.dbo.Descriptions b on a.ID = b.ID;
Just an example, not an actual query from our system... but hopefully you get the point. All four environments live on their own SQL servers so I can gracefully move code from bottom to top without any changes.
Now we're looking at possibly combining the bottom three environments on to the same SQL Server Instance (Prod will keep its own server), so all six databases will be on the same server together. In doing this the database names will have a suffix of their type, so Database1_Dev and Database2_Dev for example.
Well there lies the issue, all queries using just Database1 and Database2 will now break, and if I do change them to use Database1_Dev and Database2_Dev at the lowest level I can't just move them up to the next level Database1_Sandbox and Database2_Sandbox without modifying the queries.
The options I'm looking at are requesting three SQL instances on this server - which I'm sure will get shot down - or changing the queries to use dynamic SQL where I can pass in the DB name as a variable. I don't like either option.
Synonyms are the only thing I can think of that would allow a different name to be used, but this is going the wrong direction. I don't need one DB to have multiple names, rather multiple databases to have the same name within the same context. So like if in a procedure I could pass in the environment and I could alias Database1 to Database1_Sandbox just within the transaction or query. I don't think there is any way to do this, but I thought I'd ask.
Thanks for any suggestions.
Is it the default for a View to reference base tables in its own database in SQL Server Management Studio if it doesn't explicitly point to a specific database? I have tables with the same names across several databases on the same server and I'm not sure how to check which tables it's using. I used this query to see the Table_Catalog:
SELECT view_name, Table_Name,* FROM INFORMATION_SCHEMA.VIEW_TABLE_USAGE
However I saw a warning that querying the sys.objects is the only way to really confirm the dependencies but I don't have a good query to see database information.
Appreciate any help. Thank you.
A view same as any query will reference tables from it's own database unless database name is explicitly mentioned with the table name like databaseOne.dbo.TableName
My original question was about whether to keep separate ASPNETDB.MDF from the application database or merge all the tables in one database. Checking the previous questions/answers, I learned that it depends on whether the membership data would be shared across several applications.
Now, my question is this. In case I decide to keep ASPNETDB.MDF separate from the application DB, how can I query 2 tables located in 2 different databases?
Thanks for helping.
If you have two databases/schemas on the same database server, you can query across databases with the following syntax:
select *
from database1.dbo.table1 t1 join database2.dbo.table2 t2 on
t1.field1 = t2.field2
If they are on physically separate servers, you can still do a cross-database query, but you need to link the servers first:
http://msdn.microsoft.com/en-us/library/aa213778(v=sql.80).aspx
You can check your SQL Server version by:
SELECT SERVERPROPERTY('Edition')
If you are using "SQL Azure" you will not be able to use a table from different database. You will get this error:
Reference to database and/or server name in 'DataBase.Schema.Table' is not supported in this version of SQL Server.
Even if you try to Query a different database from your file like this:
USE ANOTHER_DATABASE;
You will get this error:
USE statement is not supported to switch between databases. Use a new connection to connect to a different database.
In the SQL Server 2005 books online section "Defining Named Queries in a Data Source View (Analysis Services)", it states:
A named query can also be used to join multiple database tables from one or more data sources into a single data source view table.
Does anyone know where I can find examples or tutorials on how this can be done?
EDIT: To provide some additional background...
I am working with an analysis services project in the SQL Server Business Intelligence Development Studio for SQL Server 2005. I have defined a data source for each of my databases which are on different servers. I am trying to create a named query which will be a union of a table from each data source. The problem is that the named query requires me to choose a single data source for the query. The query is executed against this data source which does not know anything about the data sources in my project. However, according to the SQL Server 2005 books online, what I am trying to accomplish should be possible based on my quote from above.
MSDN has this link describing Named Queries and this link walking you through the process of creating one.
Edit: I think that to use multiple datasources, you would need to fully qualify your table to hit other datasources when creating your query, like this:
SELECT user_id, first_name, 'DB1' as DB FROM users
UNION
SELECT user_id, first_name, 'DB2' as DB FROM Database2Name.dbo.users
to get results like
user_id first_name DB
1 Bob DB1
2 Joe DB1
11 Greg DB2
12 Mark DB2
If by "multiple data sources" you mean multiple databases, then you can do this if you fully qualify the database name.
For example if I have two databases I can do this:
SELECT * FROM DatabaseA.dbo.SomeTable
JOIN DatabaseB.dbo.OtherTable
ON DatabaseA.dbo.SomeTable.Id = DatabaseB.dbo.OtherTable.Id
Make sure that you don't forget the dbo bit (the owner), otherwise it won't work.
The only other sort of "multiple data sources" that I'm aware of is distributed queries which allows you to perform queries over multiple remote instances of sql server:
sp_addlinkedserver 'server\instance'
SELECT * FROM [server\instance].DatabaseA.dbo.SomeTable
JOIN DatabaseB.dbo.OtherTable
ON [server\instance].DatabaseA.dbo.SomeTable.Id = DatabaseB.dbo.OtherTable.Id
Is there any way to use a query and join two tables that is in two different database on the same server for DbVisualizer? I used the following for the SQL server
Select * from table union select * from datbase.dbo.table2
I tried this for the DbVisualizer, and it didnt work. How do I do this?
If the databases are in different servers you need to make sure that they are set up as linked servers.
Also be warned that the optimizer is relatively weak in this scenario, same server or not. The problem is that the statistics used for weighting costs of different operations aren't necessarily meaningful between different databases, especially at the point where the two databases will "intersect". So performance isn't what it could be.
If DBVisualizer supports views, manually setup a view of table2 in your database.
create view table2 as select * from database.dbo.table2
I dont think it can be done. I resolved the situation, by running a nightly data transfer to the SQL server. I do the union select from there...