In order to use dependent fields you must have Power Scripts for Jira app installed and enabled.
To use the screen values for a field in the data source, add it as a dependent field.
Example
Let's say we have two custom fields: PCF-PRO - Single Autocomplete and PCF-PRO - Multiple Autocomplete, and the second field is populated depending on the value of the first one.
For instance, the first custom field has five options representing the five continents, and the second one contains the countries from the countries table, depending on the value selected on the first one.
The following data source represents the first custom field:
return {"AFRICA", "ASIA", "EUROPE", "AMERICA", "OCEANIA"};
The following data source represents the second custom field:
string x = argv["customfield_10101"];
string[] res = sql("myDB", "select country from countries where continent like '" + x + "'");
return res;
The following result will be on the issue view screen:
You can find a similar example here.
For the moment, dependent fields can only be used by the two custom fields with autocomplete.
Starting with Power Custom Fields PRO 4.0.0, you can use the dependent fields on SQL data sources as well.
In order to get the value set on the screen for one custom field, refer it like this: "argv[customfield_id]"