I have a query that currently runs successfully on SQL Server Management Studio, gathering information from 2 databases on the SQL server where I run the query, and one database on a linked SQL Server. The query has this structure:
SELECT TOP 10
DB1.id_number as BLN,
DB1.field1,
DB2.field2,
DB3.field3
FROM
LinkedServer.database1.dbo.table1 DB1
INNER JOIN
database2.dbo.table2 DB2 ON DB1.id_number = DB2.id_number
INNER JOIN
database3.dbo.table3 DB3 ON DB3.id_number2 = DB1.id_number2
WHERE
DB1.id_number IS NOT NULL
AND DB1.field1 IS NOT NULL
How can I run this same query from a .Net application? I am looking for a solution that doesn't require saving a View on the database.
In whatever solution you propose, please detail connection strings and security issues.
Thank you.
You can run the query using SqlCommand. Although doing it with an ORM may be a little tricky, if it even can be done.
Related
I have connected Oracle database with an Azure SQL Server database via a database link.
I am trying to fetch the data of Azure SQL Server database in Oracle and it is working fine.
But when I am joining one Oracle table and one Azure SQL Server table it is taking too much time to fetch the records.
For example:.
I have one table temp_one in Oracle database and one table temp_two in Azure SQL Server database having dblink like temp.sql.hl.com.
I joined them.
SELECT "EmpAddress",EMPLOYEE_ID
FROM temp_one a
INNER join temp_two#temp.sql.hk.com b
on a.EMPLOYEE_ID = b."EmpID";
Even this normal join is taking 8 seconds.
Note: I am trying to fetch the data in Oracle.
Please help me to resolve it.
We have developed a set of operational reports long back ago based on the SQL server , Currently we have added a third party source which has Oracle as source and we need to modify our existing SQL queries to pull the partial data from oracle as well. The tricky part of the requirement is we have different table from different source belong to single query
for example
SELECT A.ID , B.Name
FROM A --Belong to SQL server
INNER JOIN B --Belong to Oracle server
On A.id=B.id
I know we can have a linked server facility in SQL which allows us to grab the table B in some temp table and then join the SQL table with the temp table.
I just want to know is there any better approach to accomplish this as this would be very difficult to deal with the complex queries in case of this , Specially the sub queries and recursive queries.
Is creating a staging table with all required field from oracle and then use it in queries makes sense? as we are dealing with the operational data (though in most of the cases it is 1 day old,So we can do this).
We are using SSIS,SSRS and SQL serer 2008 R2 as development environment.
Thanks.
I have a question about how to perform database queries against different database systems?
For example, I have a following SQL query string:
SELECT A.F1, A.F2, B.F3, B.F4
FROM TableA A, TableB B
WHERE A.ID=B.ID AND B.ID=xyz
Is there any solution that I can perform the above query when:
TableA is from an Oracle database, TableB is also from an Oracle database from another instance
TableA is from a SQL Server database, TableB is from an Oracle database
TableA is from an Oracle database, TableB is from a SQL Server database
TableA is from a SQL Server database, TableB is also from a SQL Server database from another SQL Server instance
I know that for situation #1 I can use the ORACLE DATABASE LINK feature (also maybe #3). But is there any common solution which can address all of the scenarios above? For instance, maybe there is another scenario that I want to join two tables from MySQL and SQL Server databases.
For coding I am using C#/.NET, any recommendation is welcome, including joining the data in the code.
Thanks!
This is known as a federated query
You can use SQL Servers federation ability (linked servers) and run the query in SQL Server. You can use Oracles federation ability (Oracle heterogeneous services) and run the query in Oracle.
Either way you need to pick a database server, make the other (foreign) database known to that server then execute the query on the server.
Keep in mind you cannot expect good performance from this as in most cases the executing server is loading all the source records locally and joining locally.
Otherwise you need to write your own 'federation' ability in your app. This is non trivial, i.e. data types don't match exactly between vendors so you need to build some smarts. Also if you are joining particularly large tables you'd better make sure your algorithm is optimised or you'll run our of memory. Further to this, federated query ability in existing products (SQL, Oracle, Cognos etc.) is the result of very large companies doing a lot of development.
Can you tell us how many records you expect to join, and are the various source database servers mostly fixed or is this for an ad hoc query tool?
I am trying to find a way of linking data from two servers in SSRS report builder 2.0
ultimately using one dataset to query 2 databases in 2 different servers.
The SQL that i have is very basic as shown below and i can run the query easily in SQL management studio.
select * from
[server1].[DES].[dbo].[Daily] dr
LEFT JOIN [server2].[VES].[dbo].[Rou] mr
ON dr.ID = mr.id
Also the access i have to the reporting server is read only so i cant really make any administrative changes to the configuration.
I have explored the connection string to create a connection but it only allows me to connect to one server for each dataset. what i am trying to do is use one dataset
Any help will be greatly appreciated as i am a junior in SQL and SSRS
Using SSRS and MS SQL 2008 R2
if you executing this query from your SSMS it means this other server
is a linked server. then it should be no different to execute it from
SSRS.
Yes it is right you can only add one server to your data source of
your dataset whether its a shared data source or embedded.
But for instance if you have a data source pointing to say Server A
when you executing queries which will be pulling data from Server A
and also from server B you will Use fully Qualified name for the
Objects from server B and two part name from server A.
something like this ...
SELECT *
FROM Schema.Table_Name A INNER JOIN [ServerNameB].DataBase.Schema.TableName B
ON A.ColumnA = B.ColumnA
obviously ServerB has to be a Linked Server.
I can think of two possible solutions
Option 1:
Creating a stored procedure on server1 (With a query accessing the another server). And call this stored procedure from SSRS (Dataset).
Option 2:
Create two dataset with two different connection strings on the RDL (one for Server1 and another for Server2).
Use the "LookUpDataSet" function in Report Builder to merge the results using the key fields.
Option 2 is preferable.
Problem: I have to pull data from a SQL Server database and an Oracle database and put it together in one dataset. The problem I have is: The SQL Server query requires an ID that is only found from the return of the Oracle query.
What I am wondering is: How can I approach this problem in a way such that performance is not harmed?
You can do this with linked servers or by transferring the data all to one side. It's all going to depend on the volume of data on each side.
A general rule of thumb is to execute the query on the side which has the most data.
For instance, if the set of Oracle IDs is small, but the SQL Server set is large, you make a linked server to the Oracle side and execute this on the SQL Server side:
SELECT *
FROM sqlservertable
INNER JOIN linkedserver.oracletable
ON whatever
In this case, if the Oracle side is large (or cannot be prefiltered before the need to join with the SQL Server side), the performance will normally be pretty poor - and will improve a lot by pulling the entire table (or the minimal subset you can determine) into a SQL Server table instead and do the JOIN all on the SQL Server side.