About Manual Joins

There are two types of manual joins in GE Digital APM:

• Manual Inner Join: Returns a row for every record where the values in the joined fields in both families are equal. An inner join returns only those records that satisfy the join conditions, so any unmatched records are dropped from the result set.
• Manual Outer Join: Returns a row for every record in one family, and a row for every record where the values in the joined fields in both families are equal. An outer join can be either a left outer join or a right outer join. When you add query sources to the grid in the Conditions section and join their fields, the family that you added first is referred to as Table #1, and the family that you added second is referred to as Table #2.
  • A left outer join returns every record in Table #1, regardless of whether each record is linked to a record from Table #2. The results also include the records in Table #2 in which the value in the joined field is equal to that in Table #1.
  • A right outer join returns every record in Table #2, regardless of whether each record is linked to a record in Table #1. The results also include the records in Table #1 in which the value in the joined field is equal to that in Table #2.

The following table shows the line styles that appear in the design canvas to represent manual joins.

Join Type	Line Style
Manual Inner Join
Manual Outer Left Join
Manual Outer Right Join

Suppose that you notice that two pieces of equipment, such as a centrifugal pump and an air cooled heat exchanger, have been malfunctioning recently. You suspect that the failures could be caused by human error during installation. You decide to query the database to find instances where these pieces of equipment were installed on the same day by the same person.

To do so, you would need to add the Centrifugal Pump family and the Air Cooled Heat Exchanger family as query sources. You would then need to join the Asset Installation Date fields and the Responsible Installer fields between the two families via an inner join. Doing so would return only records where a centrifugal pump was installed by the same person on the same date as an air cooled heat exchanger.