winform+SQL server聊天工具，聊天时可发文件、语音、表情包；可查询历史聊天记录；具体过程+代码实现

由于实现一个完整的聊天工具涉及到很多技术，我无法在这里提供完整的过程和代码实现。但我可以为您提供一些指导，帮助您了解一些关键技术和步骤。

1. 建立数据库表格

在SQL Server中建立用户信息表和聊天记录表，可以使用以下代码：

-- 用户信息表
CREATE TABLE [dbo].[Users](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [Username] [nvarchar](50) NOT NULL,
    [Password] [nvarchar](50) NOT NULL,
    [Nickname] [nvarchar](50) NOT NULL,
    CONSTRAINT [PK_Users] PRIMARY KEY CLUSTERED 
    (
        [Id] ASC
    )
)

-- 聊天记录表
CREATE TABLE [dbo].[ChatMessages](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [SenderId] [int] NOT NULL,
    [ReceiverId] [int] NOT NULL,
    [MessageType] [int] NOT NULL,
    [MessageContent] [nvarchar](max) NOT NULL,
    [SendTime] [datetime] NOT NULL,
    CONSTRAINT [PK_ChatMessages] PRIMARY KEY CLUSTERED 
    (
        [Id] ASC
    )
)

2. 编写客户端程序和服务端程序

客户端和服务端程序可以使用C#语言编写，采用Socket通信，实现TCP/IP协议的通信。客户端和服务端程序的基本框架如下：

// 客户端程序
public class ChatClient
{
    private Socket clientSocket;

    public ChatClient()
    {
        // 创建Socket对象
        clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
    }

    // 连接服务器
    public void Connect(string ip, int port)
    {
        var endPoint = new IPEndPoint(IPAddress.Parse(ip), port);
        clientSocket.Connect(endPoint);
    }

    // 发送消息
    public void SendMessage(string message)
    {
        var buffer = Encoding.UTF8.GetBytes(message);
        clientSocket.Send(buffer);
    }

    // 接收消息
    public string ReceiveMessage()
    {
        var buffer = new byte[1024];
        var length = clientSocket.Receive(buffer);
        return Encoding.UTF8.GetString(buffer, 0, length);
    }
}

// 服务端程序
public class ChatServer
{
    private Socket serverSocket;
    private Dictionary<int, Socket> clientSockets;

    public ChatServer()
    {
        // 创建Socket对象
        serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        clientSockets = new Dictionary<int, Socket>();
    }

    // 启动服务器
    public void Start(int port)
    {
        var endPoint = new IPEndPoint(IPAddress.Any, port);
        serverSocket.Bind(endPoint);
        serverSocket.Listen(10);
        serverSocket.BeginAccept(AcceptCallback, null);
    }

    // 接受客户端连接
    private void AcceptCallback(IAsyncResult ar)
    {
        var clientSocket = serverSocket.EndAccept(ar);
        var clientId = clientSocket.GetHashCode();
        clientSockets.Add(clientId, clientSocket);
        clientSocket.BeginReceive(new byte[1024], 0, 1024, SocketFlags.None, ReceiveCallback, clientSocket);
        serverSocket.BeginAccept(AcceptCallback, null);
    }

    // 接收客户端消息
    private void ReceiveCallback(IAsyncResult ar)
    {
        var clientSocket = (Socket)ar.AsyncState;
        var clientId = clientSocket.GetHashCode();
        var length = clientSocket.EndReceive(ar);
        var message = Encoding.UTF8.GetString((byte[])ar.AsyncState, 0, length);
        // 处理客户端发送的消息
        // ...
        clientSocket.BeginReceive(new byte[1024], 0, 1024, SocketFlags.None, ReceiveCallback, clientSocket);
    }

    // 发送消息给指定客户端
    public void SendMessage(int clientId, string message)
    {
        var clientSocket = clientSockets[clientId];
        var buffer = Encoding.UTF8.GetBytes(message);
        clientSocket.Send(buffer);
    }

    // 发送消息给所有客户端
    public void SendMessageToAll(string message)
    {
        foreach (var clientSocket in clientSockets.Values)
        {
            var buffer = Encoding.UTF8.GetBytes(message);
            clientSocket.Send(buffer);
        }
    }
}

3. 实现聊天功能

实现聊天功能需要在客户端和服务端程序中增加一些具体实现，包括：

- 实现用户登录、注册、注销等操作；
- 实现聊天窗口的UI设计；
- 实现文本聊天、文件传输、语音传输、表情包等功能的具体实现。

这些功能的具体实现需要涉及到很多技术，包括界面设计、多线程编程、网络编程、音频编解码等等。在这里无法一一列举，您可以参考一些开源的聊天工具，比如Pigeon、LAN Messenger等。

4. 实现消息的存储和查询

在服务端程序中实现消息的存储和查询，需要使用ADO.NET技术连接SQL Server数据库，并且使用SQL语句进行数据的增删查改操作。具体实现可以参考以下代码：

public class ChatMessageRepository
{
    private string connectionString;

    public ChatMessageRepository(string connectionString)
    {
        this.connectionString = connectionString;
    }

    // 存储聊天记录
    public void SaveChatMessage(ChatMessage message)
    {
        using (var connection = new SqlConnection(connectionString))
        {
            connection.Open();
            var command = new SqlCommand("INSERT INTO ChatMessages (SenderId, ReceiverId, MessageType, MessageContent, SendTime) VALUES (@SenderId, @ReceiverId, @MessageType, @MessageContent, @SendTime)", connection);
            command.Parameters.AddWithValue("@SenderId", message.SenderId);
            command.Parameters.AddWithValue("@ReceiverId", message.ReceiverId);
            command.Parameters.AddWithValue("@MessageType", message.MessageType);
            command.Parameters.AddWithValue("@MessageContent", message.MessageContent);
            command.Parameters.AddWithValue("@SendTime", message.SendTime);
            command.ExecuteNonQuery();
        }
    }

    // 查询聊天记录
    public List<ChatMessage> GetChatMessages(int senderId, int receiverId, DateTime startTime, DateTime endTime)
    {
        var messages = new List<ChatMessage>();
        using (var connection = new SqlConnection(connectionString))
        {
            connection.Open();
            var command = new SqlCommand("SELECT * FROM ChatMessages WHERE (SenderId = @SenderId AND ReceiverId = @ReceiverId) OR (SenderId = @ReceiverId AND ReceiverId = @SenderId) AND SendTime BETWEEN @StartTime AND @EndTime", connection);
            command.Parameters.AddWithValue("@SenderId", senderId);
            command.Parameters.AddWithValue("@ReceiverId", receiverId);
            command.Parameters.AddWithValue("@StartTime", startTime);
            command.Parameters.AddWithValue("@EndTime", endTime);
            var reader = command.ExecuteReader();
            while (reader.Read())
            {
                var message = new ChatMessage();
                message.Id = reader.GetInt32(reader.GetOrdinal("Id"));
                message.SenderId = reader.GetInt32(reader.GetOrdinal("SenderId"));
                message.ReceiverId = reader.GetInt32(reader.GetOrdinal("ReceiverId"));
                message.MessageType = reader.GetInt32(reader.GetOrdinal("MessageType"));
                message.MessageContent = reader.GetString(reader.GetOrdinal("MessageContent"));
                message.SendTime = reader.GetDateTime(reader.GetOrdinal("SendTime"));
                messages.Add(message);
            }
        }
        return messages;
    }
}

总之，实现一个完整的聊天工具需要涉及到很多技术和步骤，需要具备比较全面的软件开发技能。如果您有具体的问题需要解答，可以提出来，我会尽力帮助您。