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问题。在我的 app.config 数据库路径中似乎很好，但在表单上，​​我收到了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";

数据库无法正常工作；它无法在退出时保存数据。然而这工作正常：

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：此错误表示连接打开。我不明白为什么这也不起作用：

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;

请人帮忙。我要疯了。

Answer 1

首先，您可以使用@“符号”来避免使用太多转义字符。 那么，“DataDirectory”变量是在哪里定义的呢？

Answer 2

.NET 有一个 connection string builder 类。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。