Custom fields table

sql/custom_fields.sql

@@ -0,0 +1,4 @@
+create table custom_fields(
+    id INTEGER PRIMARY KEY,
+    name TEXT not null
+);

src/data_provider/sqlite.rs

@@ -21,6 +21,7 @@ fn create_tables(conn: &Connection) {
     make_words(conn).expect("Failed to init table");
     make_card_stats(conn).expect("Failed to init table");
     make_history(conn).expect("Failed to init table");
+    make_custom_fields(conn).expect("Failed to init table");
 }
 
 fn make_settings(conn: &Connection) -> Result<(), rusqlite::Error> {
@@ -58,6 +59,12 @@ fn make_history(conn: &Connection) -> Result<(), rusqlite::Error> {
     Ok(())
 }
 
+fn make_custom_fields(conn: &Connection) -> Result<(), rusqlite::Error> {
+    let query = include_str!("../../sql/custom_fields.sql");
+    conn.execute(query, ())?;
+    Ok(())
+}
+
 pub fn default_connection() -> Connection {
     let db_file = db_path();
     let connection = Connection::open(db_file).expect("Failed to open database");