在C#中使用Linq Lambda更新多个记录 [英] Updating Multiple records using Linq Lambda in C#

问题描述

我有一个ThresholdTable表，其中有两列ID varchar(max)和Value varchar(max)

I have a ThresholdTable table with two columns ID varchar(max) and Value varchar(max)

ID |  Value
----------------
1  |  0701224225
2  |  0701224012

我想将其更新为

ID |  Value
----------------
1  |  105394
2  |  105595

如何通过C#，Linq，Lambda表达式实现.

How I can achieve through C#, Linq, Lambda expression.

我正在这样做，

private const string ThresholdValue1 = "1";

private const string ThresholdValue2 = "2";

var Setting = this.context.ThresholdTable.Where(p => p.ID.Equals(ThresholdValue1) || p.ID.Equals(ThresholdValue2));
foreach (var s in Setting)
{
    if (s.ID.Equals(ThresholdValue1))
    {
        s.Value = "105394";
    }
    else if (s.ID.Equals(ThresholdValue2))
    {
        s.Value = 105595;
    }
    this.context.SaveChanges();
}

请给我建议一些更好的方法.

Please suggest me some better way.

推荐答案

Linq用于查询数据，而不用于更新数据.

Linq is for querying data, not for updating them.

现在，为了更好地替代代码，如果要更新的值很多，可以将所需的值放在Dictionary中，并在循环遍历它们的同时更新值，例如

Now, for a better alternative of your code, if you many values to update, you can put your desired values in a Dictionary and update your values while looping through them like

var valuesToPopulate = new Dictionary<string, string> { 
    { "1", "105394" }, 
    { "2", "105595" } 
};

foreach (var threashold in this.context.ThresholdTable)
{
    var valueToPopulate = valuesToPopulate.FirstOrDefault(d => d.Key.Equals(threashold.ID.Equals));
    if (!valueToPopulate.Equals(new KeyValuePair<string, string>()))
        threashold.Value = valueToPopulate.Value;
}
this.context.SaveChanges();

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