Join: inner join, right outer join, left outer join, full outer join

In this section we describe the basic concept of join - with its declinations of inner join, left outer join, right outer join, and full outer join - and the way it is implemented in KNIME with the Joiner node.

Indeed, the join mode is not the only parameter to set for a join. You also need to identify the key column(s), the columns you want to keep into the output table, and a number of strategies to deal with duplicate values.

Reference workflow is on the EXAMPLES server under:
02_ETL_Data_Manipulation/03_Joining_and_Concatenating/02_Joiner02_ETL_Data_Manipulation/03_Joining_and_Concatenating/02_Joiner^*

Exercise

• Read adult.csv data set. Then calculate the average age and number of rows for the 4 groups defined by (sex, income) and join the corresponding 2 aggregated values to each row in the group.