实现MQTT关联变量的别名问题，实现了，同个变量发给不同的MQTT服务器的名称不同

Data/Entities/DbVariableMqtt.cs

@@ -0,0 +1,54 @@
+using System;
+using SqlSugar;
+
+namespace PMSWPF.Data.Entities;
+
+/// <summary>
+/// 表示变量数据与MQTT服务器之间的关联实体，包含MQTT别名。
+/// </summary>
+[SugarTable("VariableMqtt")]
+public class DbVariableMqtt
+{
+    /// <summary>
+    /// 关联的唯一标识符。
+    /// </summary>
+    [SugarColumn(IsPrimaryKey = true, IsIdentity = true)]
+    public int Id { get; set; }
+
+    /// <summary>
+    /// 关联的变量数据ID。
+    /// </summary>
+    public int VariableDataId { get; set; }
+
+    /// <summary>
+    /// 关联的MQTT服务器ID。
+    /// </summary>
+    public int MqttId { get; set; }
+
+    /// <summary>
+    /// 变量在该MQTT服务器上的别名。
+    /// </summary>
+    public string MqttAlias { get; set; } = string.Empty;
+
+    /// <summary>
+    /// 创建时间。
+    /// </summary>
+    public DateTime CreateTime { get; set; } = DateTime.Now;
+
+    /// <summary>
+    /// 更新时间。
+    /// </summary>
+    public DateTime UpdateTime { get; set; } = DateTime.Now;
+
+    /// <summary>
+    /// 导航属性：关联的变量数据。
+    /// </summary>
+    [Navigate(NavigateType.ManyToOne, nameof(VariableDataId))]
+    public DbVariableData? VariableData { get; set; }
+
+    /// <summary>
+    /// 导航属性：关联的MQTT服务器。
+    /// </summary>
+    [Navigate(NavigateType.ManyToOne, nameof(MqttId))]
+    public DbMqtt? Mqtt { get; set; }
+}

Data/Repositories/VariableMqttAliasRepository.cs

@@ -0,0 +1,123 @@
+using PMSWPF.Data.Entities;
+using SqlSugar;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace PMSWPF.Data.Repositories;
+
+/// <summary>
+/// 变量与MQTT服务器别名关联的数据仓库。
+/// </summary>
+public class VariableMqttAliasRepository
+{
+    /// <summary>
+    /// 根据变量ID和MQTT服务器ID获取别名。
+    /// </summary>
+    /// <param name="variableDataId">变量数据ID。</param>
+    /// <param name="mqttId">MQTT服务器ID。</param>
+    /// <returns>DbVariableMqtt实体，如果不存在则为null。</returns>
+    public async Task<DbVariableMqtt?> GetAliasByVariableAndMqtt(int variableDataId, int mqttId)
+    {
+        using (var db = DbContext.GetInstance())
+        {
+            return await GetAliasByVariableAndMqtt(variableDataId, mqttId, db);
+        }
+    }
+
+    /// <summary>
+    /// 根据变量ID和MQTT服务器ID获取别名。
+    /// </summary>
+    /// <param name="variableDataId">变量数据ID。</param>
+    /// <param name="mqttId">MQTT服务器ID。</param>
+    /// <param name="db">SqlSugarClient实例。</param>
+    /// <returns>DbVariableMqtt实体，如果不存在则为null。</returns>
+    public async Task<DbVariableMqtt?> GetAliasByVariableAndMqtt(int variableDataId, int mqttId, SqlSugarClient db)
+    {
+        return await db.Queryable<DbVariableMqtt>()
+                            .Where(it => it.VariableDataId == variableDataId && it.MqttId == mqttId)
+                            .FirstAsync();
+    }
+
+    /// <summary>
+    /// 批量添加变量与MQTT服务器的关联。
+    /// </summary>
+    /// <param name="entities">要添加的DbVariableMqtt实体列表。</param>
+    /// <returns>成功添加的数量。</returns>
+    public async Task<int> AddManyAsync(IEnumerable<DbVariableMqtt> entities)
+    {
+        using (var db = DbContext.GetInstance())
+        {
+            return await AddManyAsync(entities, db);
+        }
+    }
+
+    /// <summary>
+    /// 批量添加变量与MQTT服务器的关联。
+    /// </summary>
+    /// <param name="entities">要添加的DbVariableMqtt实体列表。</param>
+    /// <param name="db">SqlSugarClient实例。</param>
+    /// <returns>成功添加的数量。</returns>
+    public async Task<int> AddManyAsync(IEnumerable<DbVariableMqtt> entities, SqlSugarClient db)
+    {
+        return await db.Insertable<DbVariableMqtt>(entities).ExecuteCommandAsync();
+    }
+
+    /// <summary>
+    /// 更新变量与MQTT服务器的别名。
+    /// </summary>
+    /// <param name="variableDataId">变量数据ID。</param>
+    /// <param name="mqttId">MQTT服务器ID。</param>
+    /// <param name="newAlias">新的别名。</param>
+    /// <returns>受影响的行数。</returns>
+    public async Task<int> UpdateAliasAsync(int variableDataId, int mqttId, string newAlias)
+    {
+        using (var db = DbContext.GetInstance())
+        {
+            return await UpdateAliasAsync(variableDataId, mqttId, newAlias, db);
+        }
+    }
+
+    /// <summary>
+    /// 更新变量与MQTT服务器的别名。
+    /// </summary>
+    /// <param name="variableDataId">变量数据ID。</param>
+    /// <param name="mqttId">MQTT服务器ID。</param>
+    /// <param name="newAlias">新的别名。</param>
+    /// <param name="db">SqlSugarClient实例。</param>
+    /// <returns>受影响的行数。</returns>
+    public async Task<int> UpdateAliasAsync(int variableDataId, int mqttId, string newAlias, SqlSugarClient db)
+    {
+        return await db.Updateable<DbVariableMqtt>()
+                            .SetColumns(it => it.MqttAlias == newAlias)
+                            .Where(it => it.VariableDataId == variableDataId && it.MqttId == mqttId)
+                            .ExecuteCommandAsync();
+    }
+
+    /// <summary>
+    /// 删除变量与MQTT服务器的关联。
+    /// </summary>
+    /// <param name="variableDataId">变量数据ID。</param>
+    /// <param name="mqttId">MQTT服务器ID。</param>
+    /// <returns>受影响的行数。</returns>
+    public async Task<int> DeleteAsync(int variableDataId, int mqttId)
+    {
+        using (var db = DbContext.GetInstance())
+        {
+            return await DeleteAsync(variableDataId, mqttId, db);
+        }
+    }
+
+    /// <summary>
+    /// 删除变量与MQTT服务器的关联。
+    /// </summary>
+    /// <param name="variableDataId">变量数据ID。</param>
+    /// <param name="mqttId">MQTT服务器ID。</param>
+    /// <param name="db">SqlSugarClient实例。</param>
+    /// <returns>受影响的行数。</returns>
+    public async Task<int> DeleteAsync(int variableDataId, int mqttId, SqlSugarClient db)
+    {
+        return await db.Deleteable<DbVariableMqtt>()
+                            .Where(it => it.VariableDataId == variableDataId && it.MqttId == mqttId)
+                            .ExecuteCommandAsync();
+    }
+}