這問題一直困擾我很久，我就想說測一下到底是啥意思 在 TableOperation 中有一個 InsertOrReplace 還有 InsertOrMerge 到底有啥不同，不如就乾脆寫一個程式測試一下它們的行為，這也對之後在設計系統上會有幫助..
前置作業 首先你要 安裝 nuget
https://www.nuget.org/packages/Microsoft.Azure.Cosmos.Table ，這邊我撰寫案例是用 .net core 3.1；在 Azure Portal 開一個
儲存體帳戶，並且在左側的存取金鑰中拿到 Connection String.
解釋案例，我會先寫入一筆資料，並且 是使用 InsertOrReplace ，我再取出來，之後再用在寫一次，這時候我有改變某些 Properties 在使用 InsertOrMerge 寫回，取出後看看答案
<![CDATA[
var tableClient = CloudStorageAccount.Parse(_ConnectionString).CreateCloudTableClient(new TableClientConfiguration());
var table = tableClient.GetTableReference("table1");
//InsertOrReplace
var sampleObject = new User("CLASSA", "DATAKEY1")
{
Name = "DONMA1-INSERTUPDATE",
Age = 1,
Meta = "META-INSERTUPDATE",
Create = new DateTime(2001, 1, 1).AddDays(1),
LastLoginDate = DateTime.Now
};
table.Execute(TableOperation.InsertOrReplace(sampleObject));
//Read Data After InsertOrReplace
Console.WriteLine("------ Read Data After InsertOrReplace ------");
var data1 = table.Execute(TableOperation.Retrieve<User>("CLASSA", "DATAKEY1")).Result;
Console.WriteLine(JsonConvert.SerializeObject(data1));
Console.WriteLine("\r\n\r\n\r\n");
//InsertOrMerge
var sampleObject2 = new User("CLASSA", "DATAKEY1")
{
Name = "DONMA1-INSERTORMERGE",
Age = null, //刻意放 null 測試
Meta = null, //刻意放 null 測試
Create = new DateTime(2020, 1, 1).AddDays(1),
LastLoginDate = null //刻意放 null 測試
};
table.Execute(TableOperation.InsertOrMerge(sampleObject2));
//Read Data After InsertOrMerge
Console.WriteLine("------ Read Data After InsertOrMerge ------");
var data2 = table.Execute(TableOperation.Retrieve<User>("CLASSA", "DATAKEY1")).Result;
Console.WriteLine(JsonConvert.SerializeObject(data2));
//Result:
// ------ Read Data After InsertOrReplace ------
//{"Name":"DONMA1-INSERTUPDATE","Age":1,"Create":"2001-01-01T16:00:00Z","Friends":[],"Meta":"META-INSERTUPDATE","LastLoginDate":"2021-01-06T01:58:46.1801935Z","PartitionKey":"CLASSA","RowKey":"DATAKEY1","Timestamp":"2021-01-06T09:58:07.4542422+08:00","ETag":"W/\"datetime'2021-01-06T01%3A58%3A07.4542422Z'\""}
//------ Read Data After InsertOrMerge ------
//{"Name":"DONMA1-INSERTORMERGE","Age":1,"Create":"2020-01-01T16:00:00Z","Friends":[],"Meta":"META-INSERTUPDATE","LastLoginDate":"2021-01-06T01:58:46.1801935Z","PartitionKey":"CLASSA","RowKey":"DATAKEY1","Timestamp":"2021-01-06T09:58:07.7934816+08:00","ETag":"W/\"datetime'2021-01-06T01%3A58%3A07.7934816Z'\""}
]]>
<![CDATA[
public class User : Microsoft.Azure.Cosmos.Table.TableEntity
{
public string Name { get; set; }
public int? Age { get; set; }
public DateTime Create { get; set; }
public List<User> Friends { get; set; }
public string Meta { get; set; }
public DateTime? LastLoginDate { get; set; }
public User()
{
Friends = new List<User>();
}
public User(string classId, string userId)
{
PartitionKey = classId;
RowKey = userId;
Friends = new List<User>();
}
}
]]>
Result:
------ Read Data After InsertOrReplace ------
{"Name":"
DONMA1-INSERTUPDATE
","Age":1,"Create":"2001-01-01T16:00:00Z","Friends":[],"Meta":"META-INSERTUPDATE","LastLoginDate":"2021-01-06T01:58:46.1801935Z","PartitionKey":"CLASSA","RowKey":"DATAKEY1","Timestamp":"
2021-01-06T09:58:07.4542422+08:00","ETag":"
W/\"datetime'2021-01-06T01%3A58%3A07.4542422Z'\""}
------ Read Data After InsertOrMerge ------
{"Name":"
DONMA1-INSERTORMERGE","Age":1,"Create":"2020-01-01T16:00:00Z","Friends":[],"Meta":"META-INSERTUPDATE","LastLoginDate":"2021-01-06T01:58:46.1801935Z","PartitionKey":"CLASSA","RowKey":"DATAKEY1","Timestamp":"
2021-01-06T09:58:07.7934816+08:00","ETag":"W/\"datetime'2021-01-06T01%3A58%3A07.7934816Z'\""}
所以結論，如果原本存在的資料，之後如果使用 InsertOrMerge ，你放空( null ) 的值，就會保留資料庫上面的，如果新的資料友值( 非 null ) 就會用新的資料代替..
reference :
https://docs.microsoft.com/zh-tw/rest/api/storageservices/insert-or-merge-entity
https://stackoverflow.com/questions/45490528/insertorupdate-vs-insertormerge-in-azure-storage-tables-what-is-the-difference
