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Transforms

1. What is transform?

In the SQLFlow, transform is the code snippet that transform the data from source to target. 

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SELECT SUM(Quantity) as total_quantity FROM OrderDetails;

The code snippet SUM(Quantity) is a transform that transform the data from the source OrderDetails.Quantity to the target total_quantity.

transform sample

Transform can be as simple as a function or as complex as a sub-query and stored procedure, it shows the data transformation relationship between the source and target, and tells you how the data is transformed.

2. How transform is organized in the data lineage model?

In the data lineage model, a transform is the sub-node of a relationship node. More than one transform can be generated for a relationship node. 

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<relationship id="2" type="fdd" effectType="function">
    <target id="11" column="SUM" parent_id="10" parent_name="SUM"/>
    <source id="5" column="Quantity" parent_id="4" parent_name="OrderDetails">
    <transforms>
        <transform type="function">
            <code>SUM(Quantity)</code>
        </transform>
    </transforms>
    </source>
</relationship>