写一个C# DBhelper类

DBHelper类在C#中通常用于封装数据库操作，简化数据访问层的代码。下面是一个简单的例子，展示了如何创建一个基本的DbHelper类，该类提供增删改查的功能：

using System.Data.SqlClient;
using System.Data;

public class DBHelper
{
    private readonly string connectionString = "your_connection_string_here"; // 替换为实际的数据库连接字符串

    public DBHelper()
    {
        // 数据库连接初始化
    }

    // 插入数据方法
    public int Insert(string tableName, Dictionary<string, object> data)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            string query = $"INSERT INTO {tableName} ({string.Join(",", data.Keys)}) VALUES ({string.Join(",", data.Values)})";
            SqlCommand command = new SqlCommand(query, connection);
            return command.ExecuteNonQuery();
        }
    }

    // 更新数据方法
    public int Update(string tableName, string keyValueColumn, object keyValue, Dictionary<string, object> updateData)
    {
        string whereClause = $"{keyValueColumn} = {keyValue}";
        string setClause = string.Join(", ", $"{k} = {v}" for (k, v) in updateData);
        string query = $"UPDATE {tableName} SET {setClause} WHERE {whereClause}";

        // ...(其余代码与Insert类似，使用SqlCommand执行更新)
    }

    // 删除数据方法
    public bool Delete(string tableName, string keyValueColumn, object keyValue)
    {
        string whereClause = $"{keyValueColumn} = {keyValue}";
        string query = $"DELETE FROM {tableName} WHERE {whereClause}";

        // ...(同理，使用SqlCommand执行删除并返回影响行数判断是否成功)
    }

    // 查询数据方法，这里仅示例了查询所有数据，可根据需要添加复杂查询
    public DataTable SelectAll(string tableName)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            SqlCommand command = new SqlCommand($"SELECT * FROM {tableName}", connection);
            SqlDataAdapter adapter = new SqlDataAdapter(command);
            DataTable dataTable = new DataTable();
            adapter.Fill(dataTable);
            return dataTable;
        }
    }
}