Fix dbt 'relationships' generic test for ClickHouse ClickHouse#19

dbt/include/clickhouse/macros/generic_tests/relationships.sql

@@ -0,0 +1,24 @@
+{% macro clickhouse__test_relationships(model, column_name, to, field) %}
+
+with child as (
+    select {{ column_name }} as from_field
+    from {{ model }}
+    where {{ column_name }} is not null
+),
+
+parent as (
+    select {{ field }} as to_field
+    from {{ to }}
+)
+
+select
+    from_field
+
+from child
+left join parent
+    on child.from_field = parent.to_field
+
+where parent.to_field is null
+settings join_use_nulls = 1
+
+{% endmacro %}