AppDbContext: Add ExecuteBatch() and ExecuteScalar()

Elwig/Helpers/AppDbContext.cs

@@ -100,6 +100,18 @@ namespace Elwig.Helpers {
             return cnx;
         }
 
+        public static async Task ExecuteBatch(SqliteConnection cnx, string sql) {
+            using var cmd = cnx.CreateCommand();
+            cmd.CommandText = sql;
+            await (await cmd.ExecuteReaderAsync()).CloseAsync();
+        }
+
+        public static async Task<object?> ExecuteScalar(SqliteConnection cnx, string sql) {
+            using var cmd = cnx.CreateCommand();
+            cmd.CommandText = sql;
+            return await cmd.ExecuteScalarAsync();
+        }
+
         protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) {
             optionsBuilder.UseSqlite(ConnectionString);
             optionsBuilder.UseLazyLoadingProxies();