`fabric__get_use_database_sql` emits invalid `USE [None];` when `database=None` (breaks `drop_schema_named`)

[sdebruyn]

Summary

fabric__get_use_database_sql has no None-guard, so callers that pass database=None (a legitimate dbt-core code path, see below) cause the macro to render USE [None]; — syntactically invalid T-SQL.

Evidence (HEAD 0de2190, v1.10.0)

dbt/include/fabric/macros/adapters/metadata.sql:

{%- macro fabric__get_use_database_sql(database) -%}
  USE [{{database | replace('"', '') | replace('[', '') | replace(']', '')}}];
{%- endmacro -%}

If database is the Python value None, Jinja renders it as the string "None".

How database=None happens in practice

This is not a hypothetical. dbt-core's default__drop_schema_named macro builds a relation with no database and hands it to drop_schema:

{% macro default__drop_schema_named(schema_name) %}
  {% set schema_relation = api.Relation.create(schema=schema_name) %}
  {{ adapter.drop_schema(schema_relation) }}
{% endmacro %}

api.Relation.create(schema=schema_name) creates a relation with relation.database = None because the caller did not specify one. drop_schema then dispatches into fabric__drop_schema, which calls fabric__get_use_database_sql(relation.database) — i.e. fabric__get_use_database_sql(None) — and the macro renders USE [None];.

User-facing triggers for this code path:

• dbt run-operation drop_schema_named --args '{schema_name: foo}' — the documented way to drop a schema by name without specifying a database.
• The BaseDropSchemaNamed test class in dbt-tests-adapter exercises this exact path.
• Any user-authored macro that calls api.Relation.create(schema=...) without a database arg and then hands the relation to a metadata helper.

User impact

A dbt run-operation drop_schema_named call fails with Invalid object name 'None'. The error appears as a generic T-SQL parsing failure with no obvious connection to dbt's database handling — users typically waste time looking at their schema name or permissions before tracing it back to the macro.

Suggested fix

Wrap the body in a None-guard:

{%- macro fabric__get_use_database_sql(database) -%}
  {%- if database is not none -%}
    USE [{{ database | replace('"', '') | replace('[', '') | replace(']', '') }}];
  {%- endif -%}
{%- endmacro -%}

Reference fix in the fork: commit dea31d36. A PR against this repo will follow.