Database Join

Description

The Database Join transform allows you to run a query against a database using data obtained from previous transforms. The parameters for this query are specified as follows:

The data grid in the transform properties dialog. This allows you to select the data coming in from the source hop. As question marks (?) in the SQL query. When the transform runs, these will be replaced with data coming in from the fields defined from the data grid. The question marks will be replaced in the same order as defined in the data grid. For example, Database Join allows you to run queries looking up the oldest person who bought a specific product as shown below:

SELECT      customernr
FROM        product_orders, customer
WHERE       orders.customernr = customer.customernr
AND         orders.productnr = ?
ORDER BY    customer.date_of_birth

The grid is then defined as follows:

When the transform runs, the (?) placeholder defined in the SQL query will be replaced with the incoming productnr field value from the source hop. To define and use multiple parameters, list the fields in order you want them to be replaced in the SQL statement.

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