protected function verifyOuter(SchemaBuilder $builder, AbstractColumn $column)
    {
        foreach ($this->findTargets($builder) as $schema) {
            $outerTable = $builder->requestTable($schema->getTable(), $schema->getDatabase());

            if (!$outerTable->hasColumn($column->getName())) {
                //Column is missing
                throw new RelationSchemaException(
                    "Unable to build morphed relation, outer key '{$column->getName()}' "
                    . "is missing in '{$outerTable->getName()}'"
                );
            }

            if ($outerTable->column($column->getName())->phpType() != $column->phpType()) {
                //Inconsistent type
                throw new RelationSchemaException(
                    "Unable to build morphed relation, outer key '{$column->getName()}' "
                    . "has different type in '{$outerTable->getName()}'"
                );
            }
        }
    }