Fixed the connection bug of getting message from table. #83

src/DotNetCore.CAP.MySql/MySqlStorageConnection.cs

@@ -57,6 +57,7 @@ SELECT * FROM `{_prefix}.published` WHERE Id=LAST_INSERT_ID();";
 
             using (var connection = new MySqlConnection(Options.ConnectionString))
             {
+                connection.Open();
                 connection.Execute("SELECT LAST_INSERT_ID(0)");
                 return await connection.QueryFirstOrDefaultAsync<CapPublishedMessage>(sql);
             }
@@ -103,6 +104,7 @@ SELECT * FROM `{_prefix}.received` WHERE Id=LAST_INSERT_ID();";
 
             using (var connection = new MySqlConnection(Options.ConnectionString))
             {
+                connection.Open();
                 connection.Execute("SELECT LAST_INSERT_ID(0)");
                 return await connection.QueryFirstOrDefaultAsync<CapReceivedMessage>(sql);
             }