如何通过SqLClient/SqlCONnection正确连接SQL Server 2014数据库？

Question

我正在将 java 应用程序转换为 .NET C#，并且正在从 JDBC 迁移到 SqlClient。我正在测试数据库连接，由于以下两个错误之一（有时是一个，有时是另一个），它失败了：

//Debug info
Loading filename: BREConfig.txt
Loading properties from file: BREConfig.txt
Properties Loaded: 23
Setting Config Values...
Server=tcp:###;Initial Catalog=Wc3Online;User ID=####;Password=####;TrustServerCertificate=True; Encrypt=False;

//Error
Connection Timeout Expired.  The timeout period elapsed while attempting to consume the pre-login handshake acknowledgement.  This could be because the pre-login handshake failed or the server was unable to respond back in time.  The duration spent while attempting to connect to this server was - [Pre-Login] initialization=13952; handshake=1056;

//Debug info
Loading filename: BREConfig.txt
Loading properties from file: BREConfig.txt
Properties Loaded: 23
Setting Config Values...
Server=tcp:####;Initial Catalog=###;User ID=####;Password=###;TrustServerCertificate=True; Encrypt=False;

//Error
A connection was successfully established with the server, but then an error occurred during the pre-login handshake. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)

我能够使用 SQL Server 身份验证通过 RDC 成功连接到数据库，如下所示：

我有一些使用 SqlClient 连接到此数据库服务器的代码：

 SqlConnection testConn = BREDBConnectionUtil.GetConnection();
            Console.WriteLine(BREDBConnectionUtil.GetConnectionString());  

            try
            {
                testConn.Open();
                Console.WriteLine("Databse Server Connected, using " + testConn.Database);
                testConn.Close();
                Console.ReadLine(); 
            } catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                Console.WriteLine(ex.StackTrace);
                Console.ReadLine();
            }

//connection string values pulled from text file and stored in objects
 private static SqlConnection con = new();
 private static readonly BREConfiguration config = BRESession.GetConfiguration();
 private static readonly Logger logger = new();

//Connect to SQL Server 2014
 private static readonly string connectionString = "Server=tcp:" + config.GetDbConnection() + ";Initial Catalog=" + config.GetDbName() + ";User ID=" + config.GetDbUser() + ";Password=" + config.GetDbPassword() + ";TrustServerCertificate=True; Encrypt=False;";


//returns an SqlConnection to connect to SQL Server 2014 database
        [MethodImpl(MethodImplOptions.Synchronized)]
        public static SqlConnection GetConnection()
        {
            con.ConnectionString = connectionString;      

            try {
                if (con.ConnectionString.Length == 0) 
                {
                    
                  con = new SqlConnection(connectionString);
                    
                }
            } catch (Exception e) {
                //print err
            } 
        return con;
        }

Answer 1

连接字符串应如下所示：

//Connect to SQL Server 2014
 private static readonly string connectionString = $"Server={config.GetDbConnection()};Initial Catalog={config.GetDbName()};User ID={config.GetDbUser()};Password={config.GetDbPassword()}";

SqlClient 字符串的前面不应有

tcp:

。还，

Encrypt=False

已经是默认值，如果您不进行加密（为什么不加密？），则不需要信任服务器证书。

---

了解连接的另一件重要事情是 C# ADO.Net 作为提供程序的一部分为您提供连接池。这意味着您不应尝试在应用程序中创建和重复使用一个连接对象。相反，为大多数查询创建并及时处置新的连接对象确实更好（好多了）......理想情况下作为

using

块的一部分。

考虑到这一点，

GetConnection()

方法应该看起来更像这样：

public static SqlConnection GetConnection()
{
    return new SqlConnection(connectionString);
}

无需想太多，每次给自己一个新对象也意味着你不必再担心同步问题。