This guide will give help you learn how to configure the Join operation for joining data from two data sources.

Configuration

To join data from two data sources, please follow these steps:

1. Drag-and-drop the source and target connectors to Apatar's work panel.
2. Drag-and-drop the Join operation node, as well.
   
   
   
   
3. Configure the connectors.

   Warning Please make sure that the fields in the two sources you are joining have different names. Otherwise, mistakes are likely to occur. There are two possible ways out of this situation: 1. Before joining the sources, use transformation to map duplicate fields to fields with unique names. In Transformation mode, click Edit Outputs, then Add from Inputs. After that, change the names of the duplicate fields. 2. Alternatively, while setting up one of the connectors, use query to change the names of the fields. A query for MS SQL, for instance, would look like this: Select field1, field2, field3 as fieldA, field4 from [table]

4. Map all the nodes together.
   
   
   
   
5. Double-click on the Join node to set its properties. The Join window will pop up.
6. You will have to choose one of the three join types by clicking on the Join Type list.
   
   
   
   
   • Inner - with this type of operation, joined are only the fields whose joining criteria match.
   • Left - if this type is selected, all the fields from the first (upper) connector are matched with fields from the second connector. If there is no match to a field from the first connector in the second connector, an empty field is created in the second connector.
   • Right - with this type, all the fields from the second (bottom) connector are matched with fields from the first connector. If there is no match to a field from the second connector in the first connector, an empty field is created in the first connector.
     For example, if the two source tables look like this:
     
     
     
     then joining them will result, depending on the type selected, in one of these tables:
     
     
     
     
7. Now you need to define the fields that will represent the criteria for joining the source tables. Switch to the Join on tab page, please.
8. Press the "+" button to set a new condition.
9. Now, choose the necessary fields. Please note that the fields in both of the two input tables must contain equal values.
   
   
   
   
10. Now switch back to the Work tab page.
11. Press the "Input Table1" layer in the left column. You will see the fields of the first source table.
12. Drag-and-drop all the fields you want to transfer from the source to the target into the Join's work area (on the left).
13. As well, drag-and-drop the output fields from the target table (on the right).
14. Map all of the corresponding fields together.
    
    
    
    
15. Now switch to another source table layer, "Input Table2".
16. Drag-and-drop the fields you want to transfer from the second input table.
17. Map them with the corresponding target fields.
    
    
    
    
18. Click "Ok".

Now you can preview the Join results or run the transformation.

Preview

To preview the output data, right-click on the Join node and choose "Preview Results". If all of the previous actions were performed correctly, you will see the output entries.

To run the transformation, either choose Run from Apatar's File menu, or right-click on the output connector and choose "Preview Results".