How to Query One Database Based on Results from Another in SSIS?

Querying a Database Based on Results from Another Database

In SSIS, retrieving data from multiple databases can be a common task. This article explores three methods to execute a query in one database based on results obtained from another:

Method 1: Using Lookup Transformation

Add a Lookup Transformation to retrieve the ID list from the first database. Select at least one column from the lookup table. However, to filter rows based on the ID list, you need to:

• Set Error Handling to Ignore Row, where rows with null values (from the lookup) will pass through.
• Use a Conditional Split to filter rows with non-null values.

Method 2: Using Script Task

This method allows you to avoid loading all data. Utilize a Script Task with VB.NET code to retrieve the ID list and store it in a user variable. Set the variable as the source for a subsequent data flow task.

Method 3: Using Execute SQL Task

Similar to Method 2, but using an Execute SQL Task to build the IN clause. Execute the following SQL command to retrieve a single result set containing the ID list and query:

DECLARE @str AS VARCHAR(4000)

SET @str = ''

SELECT @str = @str + CAST([ID] AS VARCHAR(255)) + ','
FROM dbo.MyTable 

SET @str = 'SELECT * FROM  MySecondDB WHERE ID IN (' + SUBSTRING(@str,1,LEN(@str) - 1) + ')'

SELECT @str

Store the result in a user variable and set the DataFlow Task Delay Validation property to True.

By leveraging any of these methods, you can effectively query a database based on the results obtained from another database, enabling you to perform more complex data operations within your SSIS packages.

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