I like JQL and I use every day in my job for all. I use Jira for all situations, not only for develop software, but also for NOT IT situation, like classify invoices, my equipment (laptop, mobile, printer, virtual server, etc) and I use JQL for:
JQL is used everywhere in Jira and this is a must-know feature every Jira NInja User have to know.
In several situation, we can work with date fields and ... problems starts.
we look for all the tickets created after May 8, 2018, we will find several. However, if we look for it with strict equality, then we can find nothing. the reason is : in date fields data is stored with time.
To get the data with equality, you must make a small .... "trick":
created >= '2018/05/28' and created < '2018/05/29'