diff --git a/Sources/SwiftKnex/Knex+Query.swift b/Sources/SwiftKnex/Knex+Query.swift
index f9f6eac..7f0770b 100644
--- a/Sources/SwiftKnex/Knex+Query.swift
+++ b/Sources/SwiftKnex/Knex+Query.swift
@@ -8,6 +8,13 @@
 
 extension Knex {
     
+    public func fetch<T: CollectionType>(trx: Connection? = nil) throws -> T? {
+        guard let rows = try execute(.select, trx).asResultSet() else {
+            return nil
+        }
+        return try T(rows: rows)
+    }
+    
     public func fetch<T: Entity>(trx: Connection? = nil) throws -> [T] {
         let rows = try execute(.select, trx).asResultSet()
         return try rows?.map { try T(row: $0) } ?? []
diff --git a/Sources/SwiftKnex/Protocols/Collection.swift b/Sources/SwiftKnex/Protocols/Collection.swift
new file mode 100644
index 0000000..15d897c
--- /dev/null
+++ b/Sources/SwiftKnex/Protocols/Collection.swift
@@ -0,0 +1,16 @@
+//
+//  Collection.swift
+//  SwiftJNChatApp
+//
+//  Created by Yuki Takei on 2017/02/20.
+//
+//
+
+public protocol CollectionSerializable {
+    func serialize() throws -> [[String: Any]]
+}
+
+public protocol CollectionType {
+    init(rows: ResultSet) throws
+}
+
diff --git a/Sources/SwiftKnex/Entity/Entity.swift b/Sources/SwiftKnex/Protocols/Entity.swift
similarity index 100%
rename from Sources/SwiftKnex/Entity/Entity.swift
rename to Sources/SwiftKnex/Protocols/Entity.swift