Interacting with the Database

Declaring Tables

To query a table, specify the type of its fields with a table declaration. As of writing, valid types for fields are text, int and timestamp.

table example { textField: text, intField: int, tsField: timestamp }

Yield

The yield operator -> executes a query, such as a table, and maps it to a Kuljet expression. In the expression, fields of the query can be referenced by name.

For example,

table ints { i: int }

serve get / = <ul> (ints -> <li> i)

If table ints contained values 1 to 3, the output would be:

<ul><li>1</li><li>2</li><li>3</li></ul>

Relational Operators

Tables can be queried with the select, where, order and limit operators.

example select { textField, intField = intField + 1 }

is equivalent to the SQL:

SELECT textField, intField + 1 AS intField FROM example

Note that you can name pun fields, so select { textField } is the same as select { textField = textField }.

example where intField = 1

is equivalent to the SQL:

SELECT * FROM example WHERE intField = 1

example order intField desc

is equivalent to the SQL:

SELECT * FROM example ORDER BY intField DESC

example limit 100

is equivalent to the SQL:

SELECT * FROM example LIMIT 100

example1 natJoin example2

is equivalent to the SQL:

SELECT * FROM example1 NATURAL JOIN example2

Both tables will need at least one field in common to perform a natural join, or the expression will result in a type error.

Inserting Data

An insert expression has the syntax:

insert |tableName| |expression|

where |expression| is a record matching the type of a table row.

An insert expression has type io unit, meaning it is an IO action that can be executed with the |io-expression| then |expression| form.

It is common to insert data in response to a POST request, and then redirect:

table example { a: text, b: text }

serve post / =
  fun data: { a: text, b: text } ->
     insert example data then
     redirect "/"