How Can I Execute Database Queries Based on Results from Another Database?

Executing DB Queries Based on Data from a Different Database

To execute a query in one database based on the results of a query from another database, multiple approaches can be employed:

Lookup Transformation

By adding a Lookup Transformation, you can retrieve the list of IDs from the first database. The query in the Lookup must return the ID column. While this method provides the lookup values, it doesn't filter rows based on the obtained IDs.

To filter rows with the IN condition, utilize the Lookup error output options:

• Ignore Row: Nullify the added columns from the Lookup. Use a Conditional Split to remove rows with null values in those columns.
• Redirect Row: Send all rows to the error output, effectively filtering out rows.

Script Task

To avoid loading all data, use a Script Task. This technique operates in memory and can create a comma-separated list of IDs for IN comparison. The resultant SQL command is stored in a variable and utilized as the source for subsequent operations.

Execute SQL Task

Employing an Execute SQL Task, build the IN clause dynamically. The query generates a single result set containing the modified SQL command with the comma-separated IDs. This result set serves as the source for the subsequent DataFlow Task.

Consider data type handling, especially when dealing with string values. Enclose string values in single quotes to avoid SQL injection vulnerabilities. Additionally, ensure the DataFlow Task's Delay Validation property is set to True for proper dynamic query execution.

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