Aggregating Snowflake data using ELT components
This scenario shows you an example of aggregating Snowflake data from two source
tables STUDENT and TEACHER to one target
table FULLINFO using the ELT components.
The ELT components, that is, tELTInput, tELTMap, and the tELTOutput components, are closely
related. They work jointly to generate SQL statements from database tables. The SQL
statement is then executed by the tELTOutput component to perform specified actions to a
specific database table. The Job in this scenario shows a common way in which the ELT
components are connected to generate SQL statements from multiple database tables. The
following list describes the functions of the components.
- tELTInput specifies input database table and schema. You can use multiple database tables as the input by connecting multiple tELTInput components to a tELTMap component and specifying a database table for each of the tELTInput components.
- tELTMap defines how the schema columns of the input database tables are mapped to the output columns. This component also allows you to set the mapping conditions.
- tELTOutput generates the SQL statement according to the mapping relationship defined in tELTMap and the actions (including action on table and action on data). The SQL statement is stored in the Query variable of the tELTOutput component.
In this example, context variables are used to hold all the input and output table names and connection names.