如何在连接字符串中使用变量？

Question

我在连接字符串的变量方面遇到了问题。在我的 app.config 数据库路径中似乎没问题，但在形式上，我收到该连接字符串的错误。当我尝试添加时：

_connectionString = "Data Source = (LocalDB)\MSSQLLocalDB; " +
    "AttachDbFilename = \"|DataDirectory|\gazi_db.mdf\"; " +
    "Integrated Security = True; Connect Timeout = 30";

数据库将无法正常工作；它无法在退出时保存数据。然而这很好用：

connectionString = "Data Source = (LocalDB)\MSSQLLocalDB; " +
        "AttachDbFilename = \"C:\Users\Can\Desktop\c_sharp_gazi_installer" +
        "\Gazi Installer\gazi_installer\gazi_db.mdf\"; " +
        "Integrated Security = True; Connect Timeout = 30";

我该如何解决这个问题？

编辑：我希望这会起作用

string DataDirectory = "";
string folder = Path.GetDirectoryName(System.Reflection.Assembly.GetEntryAssembly().CodeBase);
AppDomain.CurrentDomain.SetData("DataDirectory", folder);

_connectionString = _connectionString = "Data Source = (LocalDB)\MSSQLLocalDB; " +
        "AttachDbFilename = \"" + DataDirectory + "\gazi_db.mdf\"; " +
        "Integrated Security = True; Connect Timeout = 30";

但它仍然给我 sqlclient sqlexception 错误。

EDIT2: 此错误表示连接已打开。我也不明白为什么这不起作用：

SqlConnectionStringBuilder builder = new SqlConnectionStringBuilder();
builder["Data Source"] = "(LocalDB)\MSSQLLocalDB";
builder["AttachDbFilename"] = @"C:\Users\Can\Desktop\c_sharp_gazi_installer\Gazi Installer\gazi_installer\gazi_db.mdf";
builder["Integrated Security"] = true;
builder["Connect Timeout"] = 30;

请有人帮忙。我要疯了。

Answer 1

.NET 有一个 connection string builder class。使用它，您可以将每个值（即数据源、集成安全性）分别设置为变量，然后使用 .ConnectionString 属性获取连接字符串。

Answer 2

首先，你可以使用@"symbol"来避免使用这么多的转义字符。那么，你在哪里定义了"DataDirectory"变量？

如何在连接字符串中使用变量？

How can I use variable in connection string?

c#

vb.net

.net-3.5