c# - 如何检查针对 Sql Server 数据库的 linq 查询结果是否存在数据？

Question

我正在使用事件目录获取所有部门并使用 linq 查询过滤不同的部门，下面是我的代码

private static DomainController GetDomainController(string domainpath)
{
    var domainContext = new DirectoryContext(DirectoryContextType.Domain, domainpath);
    var domain = Domain.GetDomain(domainContext);
    var controller = domain.FindDomainController();
    return controller;
}

private static MyMethod()
{
    var domainController = GetDomainController(ActiveDirectorySettings.DomainPath);

    // Lookup the information in AD
    var ldapEntry = new DirectoryEntry(string.Format("LDAP://{0}", domainController)) { AuthenticationType = AuthenticationTypes.Secure | AuthenticationTypes.FastBind };
    DirectorySearcher ds;

    ds = new DirectorySearcher(ldapEntry)
    {
        SearchScope = SearchScope.Subtree,
        Filter = "(&" + "(objectClass=user)" + "(department=" + departmentname + "*))"
    };

    ds.PropertiesToLoad.Add("department");
    if (ds.FindAll().Count >= 1)
    {
        //DataSet du = DataReader.CheckAdUserExist();
        var results = ds.FindAll();
        var uniqueSearchResults = results.Cast<SearchResult>().Select(x => GetProperty(x,"department")).Distinct();
        addUsersList.AddRange(uniqueSearchResults.Select(departmentName => new UsersAndDepartments
        {
            UserDepartment = departmentName
        }));
    }
}

我想用数据库检查linq查询结果是否已经存在部门，我不知道该怎么做？

Answer 1

如果您想要使用 SqlConnection 创建一个简单的数据库连接，您只需使用从 AD 请求中收到的 department 参数查询您的数据库。

try{
    SqlConnection connection = new SqlConnection("YourConnectionstring");
    connection.Open();
    //Your connection string can be found through your Server DB
    //Now you go through your SearchResultCollection populated by SearchResult objects
    foreach(SearchResult res in uniqueSearchResult){
       SqlCommand cmd = new SqlCommand("Select * from yourTable where department=" +res.Properties["department"][0].ToString() + "", connection);
       SqlDataReader reader = cmd.ExecuteReader(); 
       //Here you verify if there are corresponding rows in your table 
       //with the request you have executed
       if(!reader.HasRows()){
           //If you have not found corresponding rows, then you add the department to your
           //list
           addUsersList.Add(res.Properties["department"][0].ToString());
       }
    }  
    connection.close();
}catch(Exception e){
    Console.WriteLine("Exception caught : \n\n" + e.ToString();
}

这应该有效。 有很多这方面的教程，但是如果您提出很多请求，我不建议您使用这种连接方法，您只会浪费太多时间/组织，也许可以尝试使用像 Entity Framework 这样的持久性框架:
https://www.codeproject.com/Articles/4416/Beginners-guide-to-accessing-SQL-Server-through-C

希望这能回答您的问题!