With this step you add columns from another table to the table, provided that they have at least one overlapping column.
Different join types are available for different use cases.
The result of an inner join contains exactly those rows that have a counterpart in both tables. If there are rows in the left or right table that have no equivalent in the other table, these rows will be lost.
No rows are lost during the full join. If there are rows without a counterpart in the left or right table, these rows will be empty in the result.
When using the left join, the rows of the left table remain completely intact. The rows of the right table only find their way into the result if they have a counterpart on the left.
When using the right join, the rows of the right table remain completely intact. The rows of the left table only find their way into the result if they have a counterpart on the right side.
Not only can you connect data sources in this way, but you can also connect other dataflows in this way, of course.
With this step you append rows from another table to the table, provided that it has the same number of columns with the same column name and data type.
Unlike the join step, the data is attached rather than linked. You just have to select the table to attach, then all columns of the table to be attached, where the name and the data type match, will be attached to the corresponding column of the original table. If there is no match of the column name or the data type does not match, the column will be ignored. In case the column names or data types do not match, you need to rename or reformat them first to make them match.
Add Lookup column
With this step you add a column from another table to the table.
You define a source column that will serve as the basis for the Lookup, as well as the Lookup data source from which the data will be taken. With the Lookup target column you specify with which column from the Lookup data source will be matched and with the Lookup return column which column will be transferred.
The new column remains empty if no match can be found for an entry in the source column in the Lookup target column. This is how you realize the requirement to find data that currently has NO correspondence in another data source. In this use case you can then filter all rows that are empty in the additional column.