{{/* Base DDL template with common structure */}}
{{- define "ddl_header" -}}
-- DDL Operation: {{comment_text .Operation}}
-- Schema: {{comment_text .Schema}}
-- Object: {{comment_text .ObjectName}}
{{- end -}}

{{- define "ddl_footer" -}}
-- End of {{comment_text .Operation}}
{{- end -}}

{{/* Base ALTER TABLE structure */}}
{{- define "alter_table_base" -}}
ALTER TABLE {{qual_table .SchemaName .TableName}}
  {{block "alter_operation" .}}{{end}};
{{- end -}}

{{/* Common existence check pattern */}}
{{- define "exists_check" -}}
DO {{dollar_delimiter}}
BEGIN
    IF NOT EXISTS (
        {{block "exists_query" .}}{{end}}
    ) THEN
        {{block "create_statement" .}}{{end}}
    END IF;
END;
{{dollar_delimiter}};
{{- end -}}

{{/* Common drop pattern */}}
{{- define "drop_if_exists" -}}
{{block "drop_type" .}}{{end}} IF EXISTS {{qual_table .SchemaName .ObjectName}};
{{- end -}}