diff --git a/src/db/sqlite/db.rs b/src/db/sqlite/db.rs
index 4444d88..09c6e51 100644
--- a/src/db/sqlite/db.rs
+++ b/src/db/sqlite/db.rs
@@ -2,30 +2,56 @@ use super::super::{
     PixivDownloaderDb, PixivDownloaderDbConfig, PixivDownloaderDbError, PixivDownloaderSqliteConfig,
 };
 use super::SqliteError;
-use rusqlite::{Connection, OpenFlags};
-use std::sync::Mutex;
+use futures_util::lock::Mutex;
+use rusqlite::{Connection, OpenFlags, OptionalExtension};
+use std::collections::HashMap;
+
+const TAGS_TABLE: &'static str = "CREATE TABLE tags (
+id INT,
+name TEXT,
+PRIMARY KEY (id)
+);";
+const VERSION_TABLE: &'static str = "CREATE TABLE version (
+id TEXT,
+v1 INT,
+v2 INT,
+v3 INT,
+v4 INT,
+PRIMARY KEY (id)
+);";
+const VERSION: [u8; 4] = [1, 0, 0, 0];
 
 pub struct PixivDownloaderSqlite {
     db: Mutex<Connection>,
 }
 
 impl PixivDownloaderSqlite {
+    /// Get all exists tables
+    async fn _get_exists_table(&self) -> Result<HashMap<String, ()>, SqliteError> {
+        let con = self.db.lock().await;
+        let mut tables = HashMap::new();
+        let mut stmt = con.prepare("SELECT name FROM main.sqlite_master WHERE type='table';")?;
+        let mut rows = stmt.query([])?;
+        while let Some(row) = rows.next()? {
+            tables.insert(row.get(0)?, ());
+        }
+        Ok(tables)
+    }
+
     fn _new(cfg: &PixivDownloaderSqliteConfig) -> Result<Self, SqliteError> {
-        let con = Connection::open_with_flags(
+        let db = Connection::open_with_flags(
             &cfg.path,
             OpenFlags::SQLITE_OPEN_READ_WRITE
                 | OpenFlags::SQLITE_OPEN_FULL_MUTEX
                 | OpenFlags::SQLITE_OPEN_CREATE
                 | OpenFlags::SQLITE_OPEN_URI,
         )?;
-        Ok(Self {
-            db: Mutex::new(con),
-        })
+        Ok(Self { db: Mutex::new(db) })
     }
 }
 
+#[async_trait]
 impl PixivDownloaderDb for PixivDownloaderSqlite {
-    #[allow(unreachable_patterns)]
     fn new<R: AsRef<PixivDownloaderDbConfig> + ?Sized>(
         cfg: &R,
     ) -> Result<Self, PixivDownloaderDbError> {
@@ -37,4 +63,8 @@ impl PixivDownloaderDb for PixivDownloaderSqlite {
             _ => panic!("Config mismatched."),
         }
     }
+
+    async fn init(&self) -> Result<(), PixivDownloaderDbError> {
+        Ok(())
+    }
 }
diff --git a/src/db/traits.rs b/src/db/traits.rs
index 29136c8..07e8a07 100644
--- a/src/db/traits.rs
+++ b/src/db/traits.rs
@@ -1,6 +1,7 @@
 use super::PixivDownloaderDbConfig;
 use super::PixivDownloaderDbError;
 
+#[async_trait]
 pub trait PixivDownloaderDb {
     /// Create a new instance of database
     fn new<R: AsRef<PixivDownloaderDbConfig> + ?Sized>(
@@ -8,4 +9,6 @@ pub trait PixivDownloaderDb {
     ) -> Result<Self, PixivDownloaderDbError>
     where
         Self: Sized + Send + Sync;
+    /// Initialize the database (create tables, migrate data, etc.)
+    async fn init(&self) -> Result<(), PixivDownloaderDbError>;
 }