c# - 在以方法作为参数的方法中传递字符串

Question

我在名为 SqlInteraction 的类中有一个方法:

public static string sqlQueryReturnString(Func<SqlConnection, string> sqlMethod)
{
    string result = "";
    SqlConnection conn = new SqlConnection();
    conn.ConnectionString = ConfigurationManager.ConnectionStrings["ApplicationServices"].ConnectionString;
    try
    {
        //open SQL connection
        conn.Open();
        result = sqlMethod(conn);
    }
    catch (Exception ex)
    {
        System.Diagnostics.Debug.Write(ex.ToString());
    }
    finally
    {
        conn.Close();
    }
    return result;
}

这是使用它的不同类中的另一个方法:

private string getPKofUserLoggedIn(SqlConnection conn, string PointPerson)
{
    int result = 0;
    SqlCommand getPKofUserLoggedIn = new SqlCommand("SELECT [PK_User] FROM [User] WHERE [LoginName] = @userIdParam", conn);
    //create and assign parameters
    getPKofUserLoggedIn.Parameters.AddWithValue("@userIdParam", PointPerson);
    //execute command and retrieve primary key from the above insert and assign to variable
    result = (int)getPKofUserLoggedIn.ExecuteScalar();
    return result.ToString();
}

我在第二种方法中传递字符串时遇到问题。如果我删除“string PointPerson”，则此调用有效:

SqlInteraction.sqlQueryReturnString(getPKofUserLoggedIn);

如何传递字符串？

Answer 1

Func<SqlConnection, string>读作“一个接受 SqlConnection 的函数”参数并返回 string ' - 如果您删除 PointPerson，那么您就拥有了。

如果要从外部方法添加参数，可以执行以下操作:

var myParam = "some string";
SqlInteraction.sqlQueryReturnString(conn => getPKofUserLoggedIn(conn, myParam));