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The syntax of queries is inspired by SQL. It can be used using Live Queries as well as via nested queries part of template expressions: Expression Language#Queries.
Let’s start with a query that demonstrates some of the supported clauses. Hover over the result and click the edit icon to show the code that generates the view:
page
order by lastModified desc
where size > 100
select name
limit 10
render [[Library/Core/Query/Page]]
It’s most convenient to use the /query Snippets to insert a query in a page.
A query is formulated specifying a querySource followed by a number of clauses that modify or restrict the result set. If you haven’t already, check out how Objects work in SilverBullet.
Every time <expression> is referenced here, an expression using the Expression Language can be used.
Clauses
where
A where clause filters out all objects that do not match a certain condition. You can have multiple where clauses if you like, which will have the same effect as combining them with the and keyword.
Here is a simple example based on a custom tag #person (see Objects on how this works):
name: John
age: 7
---
name: Pete
age: 25
To query all persons that are above age 21, we can use the following where clause:
person where page = @page.name and age > 21
order by
To sort results, an order by clause can be used, optionally with desc to order in descending order (ascending is the default):
person where page = @page.name order by age desc
limit
To limit the number of results, you can use a limit clause:
person where page = @page.name limit 1
select
You can use the select clause to select only specific attributes from the result set. You can use it either simply as select attribute1, attribute2 but also select the value of certain expressions and give them a name, even one containing spaces using the backtick identifier syntax:
person
where page = @page.name
select name, age, age + 1 as `next year`
render each and render all
In the context of Live Queries, by default, results are rendered as a table. To instead render results using Templates, use the render clause, which comes in two shapes render each where the template is instantiated for each result (the each keyword is optional):
person
where page = @page.name
render each [[internal-template/person]]
And render all where the entire result set is passed to the template as a list so the template can do its own iteration using #each, which you could then use to e.g. build a table (using this internal-template/people template, for instance):
person
where page = @page.name
render all [[internal-template/people]]