diff --git a/src/Contracts/TableSchema.php b/src/Contracts/TableSchema.php
index f1b2361..e7ffcdc 100644
--- a/src/Contracts/TableSchema.php
+++ b/src/Contracts/TableSchema.php
@@ -16,5 +16,5 @@ public function getColumns(): Collection;
     /**
      * @return Collection<int, string>
      */
-    public function getPrimaryKey(): Collection;
+    public function getPrimaryKeys(): Collection;
 }
diff --git a/src/ErdFinder.php b/src/ErdFinder.php
index 59b9d65..f95fc45 100644
--- a/src/ErdFinder.php
+++ b/src/ErdFinder.php
@@ -85,8 +85,8 @@ private function findByModels(Collection $models, array $excludes = []): Collect
             ->map(function (Collection $relations) use ($excludes) {
                 return $relations
                     ->reject(fn (Relation $relation) => $relation->excludes($excludes))
-                    ->sortBy(fn (Relation $relation) => $relation->unique())
-                    ->unique(fn (Relation $relation) => $relation->unique())
+                    ->sortBy(fn (Relation $relation) => $relation->sortByKeys())
+                    ->unique(fn (Relation $relation) => $relation->sortByKeys())
                     ->groupBy(fn (Relation $relation) => $relation->localTable());
             });
 
diff --git a/src/Relation.php b/src/Relation.php
index a46eb63..07cbb44 100644
--- a/src/Relation.php
+++ b/src/Relation.php
@@ -127,21 +127,29 @@ public function relatedRelation(): Relation
         ]));
     }
 
-    public function order(): int
+    public function sortByRelation(): int
     {
-        $orders = [
+        $relationGroups = [
             [BelongsTo::class, HasOne::class, MorphOne::class],
             [HasMany::class, MorphMany::class],
         ];
 
         $type = $this->type();
-        foreach ($orders as $index => $order) {
-            if (in_array($type, $order, true)) {
+        foreach ($relationGroups as $index => $relations) {
+            if (in_array($type, $relations, true)) {
                 return $index + 1;
             }
         }
 
-        return count($orders);
+        return count($relationGroups);
+    }
+
+    /**
+     * @return string[]
+     */
+    public function sortByKeys(): array
+    {
+        return [$this->type(), $this->localKey(), $this->foreignKey()];
     }
 
     public function uniqueId(): string
@@ -154,12 +162,4 @@ public function uniqueId(): string
 
         return implode('::', $sortBy);
     }
-
-    /**
-     * @return string[]
-     */
-    public function unique(): array
-    {
-        return [$this->type(), $this->localKey(), $this->foreignKey()];
-    }
 }
diff --git a/src/Schema/DBAL/TableSchema.php b/src/Schema/DBAL/TableSchema.php
index f524f22..e470afa 100644
--- a/src/Schema/DBAL/TableSchema.php
+++ b/src/Schema/DBAL/TableSchema.php
@@ -30,7 +30,7 @@ public function getColumns(): Collection
         return collect($this->table->getColumns())->map(fn (DBALColumn $column) => new ColumnSchema($column));
     }
 
-    public function getPrimaryKey(): Collection
+    public function getPrimaryKeys(): Collection
     {
         return collect($this->table->getIndexes())
             ->filter(fn (Index $index) => $index->isPrimary())
diff --git a/src/Schema/Laravel/TableSchema.php b/src/Schema/Laravel/TableSchema.php
index f7952cb..7f6dece 100644
--- a/src/Schema/Laravel/TableSchema.php
+++ b/src/Schema/Laravel/TableSchema.php
@@ -28,7 +28,7 @@ public function getColumns(): Collection
         return collect($this->builder->getColumns($this->name))->map(fn (array $column) => new ColumnSchema($column));
     }
 
-    public function getPrimaryKey(): Collection
+    public function getPrimaryKeys(): Collection
     {
         return collect($this->builder->getIndexes($this->name))
             ->filter(fn (array $column) => $column['primary'] === true)
diff --git a/src/Table.php b/src/Table.php
index 77e7371..d09e745 100644
--- a/src/Table.php
+++ b/src/Table.php
@@ -34,9 +34,9 @@ public function getColumns(): Collection
         return $this->schema->getColumns();
     }
 
-    public function getPrimaryKey(): Collection
+    public function getPrimaryKeys(): Collection
     {
-        return $this->schema->getPrimaryKey();
+        return $this->schema->getPrimaryKeys();
     }
 
     /**
diff --git a/src/Template/DDL.php b/src/Template/DDL.php
index 8d6bf75..8211082 100644
--- a/src/Template/DDL.php
+++ b/src/Template/DDL.php
@@ -55,7 +55,7 @@ private function renderColumn(Table $table): string
      */
     private function renderPrimaryKeys(Table $table): array
     {
-        $primaryKeys = $table->getPrimaryKey()->implode(', ');
+        $primaryKeys = $table->getPrimaryKeys()->implode(', ');
 
         return $primaryKeys ? ["PRIMARY KEY({$primaryKeys})"] : [];
     }
diff --git a/src/Template/Er.php b/src/Template/Er.php
index 55d8978..673358e 100644
--- a/src/Template/Er.php
+++ b/src/Template/Er.php
@@ -21,7 +21,7 @@
 class Er implements Template
 {
     /** @var string[] */
-    private static array $relations = [
+    private static array $relationships = [
         BelongsTo::class => '1--*',
         MorphTo::class => '1--*',
         HasOne::class => '1--1',
@@ -74,7 +74,7 @@ public function save(Collection $tables, string $path, array $options = []): int
 
     private function renderTable(Table $table): string
     {
-        $primaryKeys = $table->getPrimaryKey();
+        $primaryKeys = $table->getPrimaryKeys();
         $indexes = $table
             ->getRelations()
             ->flatMap(fn (Relation $relation) => [$relation->localColumn(), $relation->morphColumn()])
@@ -105,7 +105,7 @@ private function renderRelation(Relation $relation): string
         return sprintf(
             '%s %s %s',
             $relation->localTable(),
-            self::$relations[$relation->type()],
+            self::$relationships[$relation->type()],
             $relation->foreignTable()
         );
     }
diff --git a/tests/RelationFinderTest.php b/tests/RelationFinderTest.php
index e0ae959..d833ef0 100644
--- a/tests/RelationFinderTest.php
+++ b/tests/RelationFinderTest.php
@@ -460,7 +460,7 @@ private function draw(Collection $relations, $method): array
     {
         return $relations
             ->get($method)
-            ->sortBy(fn (Relation $relation) => $relation->order())
+            ->sortBy(fn (Relation $relation) => $relation->sortByRelation())
             ->map(fn (Relation $relation) => $this->renderRelationship($relation))
             ->toArray();
     }