Linker Issue Custom Fields
Linker Issue Custom Field is select list which allows you to select a single issue from the list. Value of this field is issue key stored by string.
When create or edit a field you can use the drop-down list or the search bar. Search is possible by summary and/or issue key (if allowed in the field settings).
If you happen to have specified an incorrect value, then it can be removed with the help of the cross button.
Searching with basic or advanced search
The basic search provides a user-friendly interface that lets you define complex queries, without needing to know how to use JQL (advanced searching).
For searching with basic search click More (1) button and find the custom field. When it appears in the line with parameters, enter the issue key (2) and press the Search (3) button.
Want more information for searching? Check out the Basic Search in Atlassian Documentation.
The advanced search allows you to build structured queries using the Jira Query Language (JQL) to search for issues. You can specify criteria that you can't define in the quick or basic searches (the ORDER BY clause, for example).
JQL is not a database query language, even though it uses SQL-like syntax.
Constructing JQL query
A simple query in JQL (also known as a 'clause') consists of a field (1), followed by an operator (2), followed by one or more values or functions (3). To search you need to click Search (4) button.
Thus, for a linker issue custom field, it will look like this:
"Linker Field" = TEST-4This query will find all issues where value of "Linker Field" field is "TEST-4".