getting custom field value which is used in parent issue withTable Grid editor

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Hello, 

I have a custom field with name "Checklist Main" (customfield id:13308) which is used in parent issue. "Checklist Main" custom filed type is Database Information. 

I have a table that name is checklit_table in PostgreSQL. The table contains two columns icode and idescription. The custom field "Checklist Main" list of data which is in icode column. 

I have another custom field with name "Checklist Main Child" which is used in sub-task issues. "Checklist Main Child" field type is Database Child Information. The field is list of data in idescription column according to selected icode from parent issue. 

I need to create a another sub-task issue type which named as Checklist. Checklist issue type have a custom filed that named as Checklist Result. I created Checklist Result custom field with Table Grid editor. 

I need to get Checklist Main daha which is selected in parent issue for table configuration.( for the field Checklist Result) Below code don't run.

gd.columns=icheckcode
gd.tablename= checklist_result
gd.ds = jira

col.icheckcode = select icode parent:id{customfield:13308} from checklist_table

How do I write configuration code for Checklist Result table?

Thanks