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SQL Query Templates

Query Templates allow you to define reusable snippets of SQL components to be used across different reports. This is useful when you have a snippet of code that gets repeated on multiple reports.

A query template is defined by 3 components:

  • name: name of template to be used in SQL reports
  • variables: dynamic parameters inside the template
  • body: content of the template

Example - Abstracting repeated components of your SQL

Say you have a report that lists all jobs, together with their statuses (stored as int in the database).

SELECT
  J.id as "ID",
  J.title as "Title"
  CASE J.status
    WHEN 0 THEN 'Running'
    WHEN 1 THEN 'Success'
    WHEN 2 THEN 'Failure'
    WHEN 3 THEN 'Created'
    ELSE 'Other' END as "Status"
FROM jobs J

You can see that the CASE WHEN J.status is something that will appear again in other reports with Status column. So we can define a {{ @job_status(status) }} query template as follows:

Then rewrite your report's SQL as:

SELECT
  J.id as "ID",
  J.title as "Title"
  {{ @job_status('J.status') }} AS "Status"
FROM jobs J

Now, whenever your report runs, the query template will automatically be replace with the actual template's content. This is just like programming language's functions inside SQL itself.

Notes

  • The |noquote in the above example is to remove the default single-quoted applying to the variable, since in this case we're referring to the actual column.
  • If you're using filter variable in your report, you can pass that variable to query template: {{{template_name(filter_var_name)}}} or {{@template_name(filter_var_name)}}.
  • Other query syntaxes ({{#if}}, etc) works fine inside your query templates.

The Benefits

  • Your SQL code now looks cleaner and more maintainable
  • When your logic changes, you just need to modify the query template once.

SQL Query Templates