FreeSql支持丰富的更新数据方法，支持单条或批量更新，在特定的数据库执行还可以返回更新后的记录值。

var connstr = "Data Source=127.0.0.1;Port=3306;User ID=root;Password=root;" + 
    "Initial Catalog=cccddd;Charset=utf8;SslMode=none;Max pool size=10";

static IFreeSql fsql = new FreeSql.FreeSqlBuilder()
    .UseConnectionString(FreeSql.DataType.MySql, connstr)
    .UseAutoSyncStructure(true) //自动同步实体结构到数据库
    .Build(); //请务必定义成 Singleton 单例模式

[Table(Name = "tb_topic")]
class Topic {
    [Column(IsIdentity = true, IsPrimary = true)]
    public int Id { get; set; }
    public int Clicks { get; set; }
    public string Title { get; set; }
    public DateTime CreateTime { get; set; }
}

更新实体

方法1：(推荐)

只更新变化的属性，依赖 FreeSql.Repository

var repo = fsql.GetRepository<Topic>();
var item = repo.Where(a => a.Id == 1).First();  //此时快照 item
item.Title = "newtitle";
repo.Update(item); //对比快照时的变化
//UPDATE `tb_topic` SET `Title` = ?p_0
//WHERE (`Id` = 1)

是不是觉得先查询再更新，啰嗦？

var repo = fsql.GetRepository<Topic>();
var item = new Topic { Id = 1 };
repo.Attach(item); //此时快照 item
item.Title = "newtitle";
repo.Update(item); //对比快照时的变化
//UPDATE `tb_topic` SET `Title` = ?p_0
//WHERE (`Id` = 1)

方法2：(原始)

var item = new Topic { Id = 1, Title = "newtitle" };
fsql.Update<Topic>()
  .SetSource(item)
  .ExecuteAffrows();
//UPDATE `tb_topic` SET `Clicks` = ?p_0, `Title` = ?p_1, `CreateTime` = ?p_2 
//WHERE (`Id` = 1)

fsql.Update<Topic>()
  .SetSource(item)
  .UpdateColumns(a => new { a.Title, a.CreateTime })
  .ExecuteAffrows();
//UPDATE `tb_topic` SET `Title` = ?p_0, `CreateTime` = ?p_1 
//WHERE (`Id` = 1)
fsql.Update<Topic>()
  .SetSource(item)
  .UpdateColumns(a => a.Title)
  .ExecuteAffrows();
//UPDATE `tb_topic` SET `Title` = ?p_0 
//WHERE (`Id` = 1)

fsql.Update<Topic>()
  .SetSource(item)
  .IgnoreColumns(a => a.Clicks)
  .ExecuteAffrows();
//UPDATE `tb_topic` SET `Title` = ?p_0, `CreateTime` = ?p_1 
//WHERE (`Id` = 1)
fsql.Update<Topic>()
  .SetSource(item)
  .IgnoreColumns(a => new { a.Clicks, a.CreateTime })
  .ExecuteAffrows();
//UPDATE `tb_topic` SET `Title` = ?p_0 
//WHERE (`Id` = 1)

var items = new List<Topic>();
for (var a = 0; a < 10; a++) items.Add(new Topic { Id = a + 1, Title = $"newtitle{a}", Clicks = a * 100 });

fsql.Update<Topic>()
  .SetSource(items)
  .ExecuteAffrows();
//UPDATE `tb_topic` SET `Clicks` = CASE `Id` WHEN 1 THEN ?p_0 WHEN 2 THEN ?p_1 WHEN 3 THEN ?p_2 WHEN 4 THEN ?p_3 WHEN 5 THEN ?p_4 WHEN 6 THEN ?p_5 WHEN 7 THEN ?p_6 WHEN 8 THEN ?p_7 WHEN 9 THEN ?p_8 WHEN 10 THEN ?p_9 END, 
//`Title` = CASE `Id` WHEN 1 THEN ?p_10 WHEN 2 THEN ?p_11 WHEN 3 THEN ?p_12 WHEN 4 THEN ?p_13 WHEN 5 THEN ?p_14 WHEN 6 THEN ?p_15 WHEN 7 THEN ?p_16 WHEN 8 THEN ?p_17 WHEN 9 THEN ?p_18 WHEN 10 THEN ?p_19 END, 
//`CreateTime` = CASE `Id` WHEN 1 THEN ?p_20 WHEN 2 THEN ?p_21 WHEN 3 THEN ?p_22 WHEN 4 THEN ?p_23 WHEN 5 THEN ?p_24 WHEN 6 THEN ?p_25 WHEN 7 THEN ?p_26 WHEN 8 THEN ?p_27 WHEN 9 THEN ?p_28 WHEN 10 THEN ?p_29 END 
//WHERE (`Id` IN (1,2,3,4,5,6,7,8,9,10))

fsql.Update<Topic>()
  .SetSource(items)
  .IgnoreColumns(a => new { a.Clicks, a.CreateTime })
  .ExecuteAffrows();
//UPDATE `tb_topic` SET `Title` = CASE `Id` WHEN 1 THEN ?p_0 WHEN 2 THEN ?p_1 WHEN 3 THEN ?p_2 WHEN 4 THEN ?p_3 WHEN 5 THEN ?p_4 WHEN 6 THEN ?p_5 WHEN 7 THEN ?p_6 WHEN 8 THEN ?p_7 WHEN 9 THEN ?p_8 WHEN 10 THEN ?p_9 END 
//WHERE (`Id` IN (1,2,3,4,5,6,7,8,9,10))

fsql.Update<Topic>()
  .SetSource(items)
  .Set(a => a.CreateTime, DateTime.Now)
  .ExecuteAffrows();
//UPDATE `tb_topic` SET `CreateTime` = ?p_0 
//WHERE (`Id` IN (1,2,3,4,5,6,7,8,9,10))

指定列更新后，SetSource 将失效

API

方法	返回值	参数	描述
SetSource	<this>	T1 \| IEnumerable<T1>	更新数据，设置更新的实体
ToSql	string		返回即将执行的SQL语句
ExecuteAffrows	long		执行SQL语句，返回影响的行数
ExecuteUpdated	List<T1>		执行SQL语句，返回更新后的记录

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来源：oschina

链接：https://my.oschina.net/u/4381592/blog/3395037

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FreeSql （十）更新数据

更新实体

API

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