This article demonstrates how to change the specifications of existing table
joins.
The following steps demonstrate how to edit the expression that defines the join to the state_abbreviations
table.
Navigate to the Data Model page of the dataset.
Click Edit Data Model to edit the
data model.
Click the (link) icon beside the
state_abbreviations connection.
The Join Details modal window appears.
Click Edit Join.
In the Edit Join modal window, the following options are available:
[Optional] Click Clear Fields to clear all already defined joins between the two tables.
[Optional] Click sample data to preview the data. Click again to hide sample data.
[Optional] Click Add Join Pair to add another column connection between the same two tables.
[Optional] Click Add Join Expression to add a join between the two tables based on a custom SQL expression.
[Optional] Click icon (minus) to
remove an existing join pair or an existing join expression.
[Optional] Under Join Expressions, click the text box to open the
Join Expression interface. There, specify or update a
custom SQL expression that defines the join conditions.
Click Apply to save the changes.
Now, let's add a join expression, and replace the original field:field join. In the
Edit Join modal window do the following:
Remove the initial join between the two columns by clicking the (minus) icon.
Under Join Expressions, click the text box to open the
Join Expression interface. Here you can specify or update the
custom SQL expression that defines the join conditions.
In the Join Expression modal window, do the following:
Enter the following expression to show only flights that have significant arrival
delay, more than five minutes:
[deststate]=[abbreviation] AND [arrdelay] > 5
Click Apply to save the expression and return to the
Edit Join modal window.
In the Edit Join modal window, do the following:
Verify that the initial join between the two columns is deleted and the new join
expression appears under Join Expressions.
Click Apply.
The Data Model interface appears. You may click
Show Data to display the updated
table.
[Optional] To revert this change prior to saving, click Undo.