AzureTable Storage 是一种用于存储大量结构化数据的服务，这些数据没有复杂的关系，并且是无模式的。存储的数据是持久的，高度可扩展的，并且可以快速检索。本文将演示如何使用C#创建一个新的Azure存储表，对表进行CRUD操作（读取、插入、更新和删除数据），以及如何删除创建的表。
表存储数据存储在跨多个存储节点的分区中。每个存储的数据实体都有一个与之关联的行键、分区键和时间戳。每个分区由一个分区键标识。在分区中，每个数据实体都与一个行键关联。分区键和行键的组合唯一地标识了一个数据实体。与数据实体相关联的时间戳跟踪了数据实体最后一次被修改的时间。行键和分区键可以由开发人员修改。时间戳由服务器管理，开发人员无法修改。
为了演示本文中的表存储操作，使用Visual Studio 2015创建了一个控制台应用程序。通过Nuget包管理器在控制台应用程序中安装了WindowsAzureStorage SDK。
创建了一个名为Customer的数据实体类。这个实体数据将被保存到表存储中。Customer类是从Microsoft.WindowsAzure.Storage.Table命名空间中的TableEntity类派生的。表存储中的每个实体数据都必须与一个分区键和行键关联。AssignPartitionKey方法将客户类型分配为分区键，AssignRowKey方法将客户ID分配为行键。
public class Customer : TableEntity
{
private int customerID;
private string customerName;
private string customerDetails;
private string customerType;
public void AssignRowKey()
{
this.RowKey = customerID.ToString();
}
public void AssignPartitionKey()
{
this.PartitionKey = customerType;
}
public int CustomerID
{
get { return customerID; }
set { customerID = value; }
}
public string CustomerName
{
get { return customerName; }
set { customerName = value; }
}
public string CustomerDetails
{
get { return customerDetails; }
set { customerDetails = value; }
}
public string CustomerType
{
get { return customerType; }
set { customerType = value; }
}
}
表存储的连接字符串包含存储帐户的名称和访问密钥，这些信息可以从Azure门户中获取。
<add key="StorageConnectionString" value="DefaultEndpointsProtocol=https;AccountName=[存储帐户名称];AccountKey=[存储帐户访问密钥]">
CloudStorageAccount.Parse方法解析连接字符串并返回一个云存储帐户对象。可以使用CloudTableClient类访问表存储中的表和实体。GetTableReference方法接受表名作为参数并返回对云表的引用。CreateIfNotExists方法在表不存在时创建一个新表。
CloudStorageAccount cloudStorageAccount = CloudStorageAccount.Parse(ConfigurationManager.AppSettings["StorageConnectionString"]);
CloudTableClient tableClient = cloudStorageAccount.CreateCloudTableClient();
Console.WriteLine("Enter Table Name to create");
string tableName = Console.ReadLine();
CloudTable cloudTable = tableClient.GetTableReference(tableName);
CreateNewTable(cloudTable);
public static void CreateNewTable(CloudTable table)
{
if (!table.CreateIfNotExists())
{
Console.WriteLine("Table {0} already exists", table.Name);
return;
}
Console.WriteLine("Table {0} created", table.Name);
}
TableOperation.Insert方法接受customer实体作为输入并返回需要对表执行的TableOperation对象。RetrieveRecord方法搜索并获取正在插入的客户实体数据。如果相同的客户数据实体已经存在，应该不执行插入操作。它是分区，通过调用customer实体类中的AssignPartitionKey和AssignRowKey方法来分配行键和分区键给数据记录。
public static void InsertRecordToTable(CloudTable table)
{
Console.WriteLine("Enter customer type");
string customerType = Console.ReadLine();
Console.WriteLine("Enter customer ID");
string customerID = Console.ReadLine();
Console.WriteLine("Enter customer name");
string customerName = Console.ReadLine();
Console.WriteLine("Enter customer details");
string customerDetails = Console.ReadLine();
Customer customerEntity = new Customer();
customerEntity.CustomerType = customerType;
customerEntity.CustomerID = Int32.Parse(customerID);
customerEntity.CustomerDetails = customerDetails;
customerEntity.CustomerName = customerName;
customerEntity.AssignPartitionKey();
customerEntity.AssignRowKey();
Customer custEntity = RetrieveRecord(table, customerType, customerID);
if (custEntity == null)
{
TableOperation tableOperation = TableOperation.Insert(customerEntity);
table.Execute(tableOperation);
Console.WriteLine("Record inserted");
}
else
{
Console.WriteLine("Record exists");
}
}
RetrieveRecord方法查询表并返回与正在查询的行键和分区键匹配的客户实体。
public static Customer RetrieveRecord(CloudTable table, string partitionKey, string rowKey)
{
TableOperation tableOperation = TableOperation.Retrieve(partitionKey, rowKey);
TableResult tableResult = table.Execute(tableOperation);
return tableResult.Result as Customer;
}
实体记录通过分区键和行键的组合唯一地标识。在更新记录之前，使用RetrieveRecord方法通过传递分区键和行键作为参数在表中搜索它。如果实体存在，则只执行更新操作。TableOperation.Replace方法执行更新操作。
public static void UpdateRecordInTable(CloudTable table)
{
Console.WriteLine("Enter customer type");
string customerType = Console.ReadLine();
Console.WriteLine("Enter customer ID");
string customerID = Console.ReadLine();
Console.WriteLine("Enter customer name");
string customerName = Console.ReadLine();
Console.WriteLine("Enter customer details");
string customerDetails = Console.ReadLine();
Customer customerEntity = RetrieveRecord(table, customerType, customerID);
if (customerEntity != null)
{
customerEntity.CustomerDetails = customerDetails;
customerEntity.CustomerName = customerName;
TableOperation tableOperation = TableOperation.Replace(customerEntity);
table.Execute(tableOperation);
Console.WriteLine("Record updated");
}
else
{
Console.WriteLine("Record does not exists");
}
}
创建并执行TableQuery对象。
public static void DisplayTableRecords(CloudTable table)
{
TableQuery tableQuery = new TableQuery();
foreach (Customer customerEntity in table.ExecuteQuery(tableQuery))
{
Console.WriteLine("Customer ID : {0}", customerEntity.CustomerID);
Console.WriteLine("Customer Type : {0}", customerEntity.CustomerType);
Console.WriteLine("Customer Name : {0}", customerEntity.CustomerName);
Console.WriteLine("Customer Details : {0}", customerEntity.CustomerDetails);
Console.WriteLine("******************************");
}
}
TableOperation.Delete创建要执行的表删除操作对象。要删除的记录通过行键和分区键标识。如果记录存在，则仅删除它。
public static void DeleteRecordinTable(CloudTable table)
{
Console.WriteLine("Enter customer type");
string customerType = Console.ReadLine();
Console.WriteLine("Enter customer ID");
string customerID = Console.ReadLine();
Customer customerEntity = RetrieveRecord(table, customerType, customerID);
if (customerEntity != null)
{
TableOperation tableOperation = TableOperation.Delete(customerEntity);
table.Execute(tableOperation);
Console.WriteLine("Record deleted");
}
else
{
Console.WriteLine("Record does not exists");
}
}
public static void DropTable(CloudTable table)
{
if (!table.DeleteIfExists())
{
Console.WriteLine("Table does not exists");
}
}