diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index acd2e8b..9b890ad 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -104,9 +104,9 @@ jobs:
     - name: Check Out
       uses: actions/checkout@v2
     - name: Build
-      run: cargo build --features server -vv
+      run: cargo build --features server,db_sqlite -vv
     - name: Run tests
-      run: cargo test --features server --verbose -- --show-output
+      run: cargo test --features server,db_sqlite --verbose -- --show-output
   build-all:
     runs-on: ubuntu-latest
     steps:
diff --git a/Cargo.toml b/Cargo.toml
index 14181a2..406af0d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -47,6 +47,7 @@ cmake = { version = "0.1", optional = true }
 all = ["db", "db_sqlite", "exif", "ugoira", "server"]
 avdict = ["bindgen", "cmake", "flagset"]
 db = []
+db_all = ["db", "db_sqlite"]
 db_sqlite = ["rusqlite"]
 exif = ["bindgen", "c_fixed_string", "cmake", "link-cplusplus", "utf16string"]
 server = ["async-trait", "db", "hyper"]
diff --git a/src/db/config.rs b/src/db/config.rs
new file mode 100644
index 0000000..bb78062
--- /dev/null
+++ b/src/db/config.rs
@@ -0,0 +1,7 @@
+pub struct PixivDownloaderDbConfig {}
+
+impl AsRef<PixivDownloaderDbConfig> for PixivDownloaderDbConfig {
+    fn as_ref(&self) -> &PixivDownloaderDbConfig {
+        self
+    }
+}
diff --git a/src/db/mod.rs b/src/db/mod.rs
new file mode 100644
index 0000000..1ff5ae4
--- /dev/null
+++ b/src/db/mod.rs
@@ -0,0 +1,20 @@
+pub mod config;
+#[cfg(feature = "db_sqlite")]
+pub mod sqlite;
+pub mod traits;
+
+pub use config::PixivDownloaderDbConfig;
+#[cfg(feature = "db_sqlite")]
+pub use sqlite::SqliteError;
+pub use traits::PixivDownloaderDb;
+pub type PixivDownloaderDbError = Box<dyn std::fmt::Display + Send + Sync>;
+
+#[cfg(feature = "db_sqlite")]
+impl From<SqliteError> for PixivDownloaderDbError {
+    fn from(e: SqliteError) -> Self {
+        Box::new(e)
+    }
+}
+
+#[cfg(not(feature = "db_sqlite"))]
+compile_error!("No database backend is enabled.");
diff --git a/src/db/sqlite/error.rs b/src/db/sqlite/error.rs
new file mode 100644
index 0000000..039396f
--- /dev/null
+++ b/src/db/sqlite/error.rs
@@ -0,0 +1,2 @@
+#[derive(derive_more::Display, derive_more::From)]
+pub enum SqliteError {}
diff --git a/src/db/sqlite/mod.rs b/src/db/sqlite/mod.rs
new file mode 100644
index 0000000..7854358
--- /dev/null
+++ b/src/db/sqlite/mod.rs
@@ -0,0 +1,3 @@
+pub mod error;
+
+pub use error::SqliteError;
diff --git a/src/db/traits.rs b/src/db/traits.rs
new file mode 100644
index 0000000..aaebf43
--- /dev/null
+++ b/src/db/traits.rs
@@ -0,0 +1,11 @@
+use super::PixivDownloaderDbConfig;
+use super::PixivDownloaderDbError;
+
+pub trait PixivDownloaderDb {
+    /// Create a new instance of database
+    fn new<R: AsRef<PixivDownloaderDbConfig> + ?Sized>(
+        cfg: &R,
+    ) -> Result<Self, PixivDownloaderDbError>
+    where
+        Self: Sized;
+}
diff --git a/src/main.rs b/src/main.rs
index 9d057b8..0743444 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -19,6 +19,8 @@ mod _ugoira;
 mod avdict;
 mod cookies;
 mod data;
+#[cfg(feature = "db")]
+mod db;
 mod download;
 mod downloader;
 mod dur;