An officially released project does not work with absolute paths. Generally, server.MapPath ("app_Data / xxx.mdb") is used to convert the path. Pay attention to the relationship between the file location of this statement and the directory in ()
Add on the <appSettings> node under Web.Config
<add key="AccessConnection" value="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|Database name.mdb"/>
Read in the program
private static readonly string connectionString=ConfigurationSettings.AppSettings["AccessConnection"].ToString();