We’ll call query.fetchNextPage() every 2 minutes while the app is in the foreground. In other words, we will request a new page of data every odd minute in the timeline., If set, this value will be used as the placeholder data for this particular query observer while the query is still in the loading data and no initialData has been provided., You must not put the ? parameter placeholders inside a quoted SQL string literals in your query. Parameters are an alternative to using string literals. I would write the query like this: WHERE f.foodcategory LIKE ? AND d.drinkvariety LIKE ?, We make use of Placeholder in forms, to show data related to the entity. For example let's say we have an EditUser page and form. We are using Placeholder as an example while viewing this page, to show some interesting live updating status about some thing based on this user., The placeholder attribute specifies a short hint that describes the expected value of an input field (e.g. a sample value or a short description of the expected format). The short hint is displayed in the input field before the user enters a value., What is placeholder data? Placeholder data allows a query to behave as if it already has data, similar to the initialData option, but the data is not persisted to the cache..