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# Azure Tables client library for Java
nn# Azure Tables client library for Java
Azure Storage Tables client library is a service that stores structured NoSQL data in the cloud, providing a
key/attribute store with a schemaless design. Tables storage gives developers flexibility and scalability with all the
best parts of Azure cloud.

[Source code][source_code] | [Package (Maven)][package] | [API reference documentation][api_documentation]
| [Product documentation][azconfig_docs] | [Samples][samples]
| [REST API documentation][rest_api] | [Product documentation][product_documentation] | [Samples][samples]

## Getting started

### Prerequisites

- Java Development Kit (JDK) with version 8 or above
- [Java Development Kit (JDK)][jdk] with version 8 or above
- [Azure Subscription][azure_subscription]
- An existing Azure storage account or Azure Cosmos DB Table API account

### Include the Package

Expand All @@ -25,17 +26,292 @@ best parts of Azure cloud.
```
[//]: # ({x-version-update-end})

### Create a Storage Account
To create a Storage Account you can use the [Azure Portal][storage_account_create_portal] or [Azure CLI][storage_account_create_cli].

```bash
az storage account create \
--resource-group <resource-group-name> \
--name <storage-account-name> \
--location <location>
```

Your storage account URL, subsequently identified as `<your-table-account-url>`, would be formatted as follows
`http(s)://<storage-account-name>.table.core.windows.net`.

### Create a Cosmos DB Table API account
To create a Cosmos DB Table API account you can use the [Azure Portal][cosmosdb_create_portal] or [Azure CLI][cosmosdb_create_cli].

```bash
az cosmosdb create \
--resource-group <resource-group-name> \
--name <cosmosdb-account-name> \
--capabilities EnableTable
```

Your Table API account URL, subsequently identified as `<your-table-account-url>`, would be formatted as follows
`http(s)://<cosmosdb-account-name>.table.cosmosdb.azure.com`.

### Authorizing requests to the Table service
Every request made to the Table service must be authorized using a connection string, shared key credential, or shared access signature. The samples below demonstrate the usage of these methods.

Note: Azure Tables doesn't support Azure Active Directory (AAD) authentication.

#### Connection string
A connection string includes the authentication information required for your application to access data in an Azure table at runtime using Shared Key authorization. See [Authorize with a connection string](#authorize-with-a-connection-string) for an example of how to use a connection string with a `TableServiceClient`.

You can obtain your connection string from the Azure Portal (click **Access keys** under **Settings** in the Portal Storage account blade, or **Connection String** under **Settings** in the Portal Cosmos DB account blade) or using the Azure CLI:

```bash
# Storage account
az storage account show-connection-string \
--resource-group <resource-group-name> \
--name <storage-account-name>

# Cosmos DB Table API account
az cosmosdb list-connection-strings \
--resource-group <resource-group-name> \
--name <cosmosdb-account-name>
```

#### Shared Key credential
Shared Key authorization relies on your account access keys and other parameters to produce an encrypted signature string that is passed on the request in the Authorization header. See [Authorize with a Shared Key credential](#authorize-with-a-shared-key-credential) for an example of how to use Shared Key authorization with a `TableServiceClient`.

To use Shared Key authorization you'll need your account name and URL, as well as an account access key. You can obtain your primary access key from the Azure Portal (click **Access keys** under **Settings** in the Portal Storage account blade, or **Connection String** under **Settings** in the Portal Cosmos DB account blade) or using the Azure CLI:

```bash
# Storage account
az storage account keys list \
--resource-group <resource-group-name> \
--account-name <storage-account-name>

# Cosmos DB Table API account
az cosmosdb list-keys \
--resource-group <resource-group-name> \
--name <cosmosdb-account-name>
```

#### Shared Access Signature (SAS)
A shared access signature allows administrators to delegate granular access to an Azure table without sharing the access key directly. You can control what resources the client may access, what permissions it has on those resources, and how long the SAS is valid, among other parameters. It relies on your account access keys and other parameters to produce an encrypted signature string that is passed on the request in the query string. See [Authorize with a Shared Access Signature (SAS) token](#authorize-with-a-shared-access-signature-sas-token) for an example of how to use shared access signatures with a `TableServiceClient`.

To use SAS token authorization you'll need your account name and URL, as well as the SAS. You can obtain your SAS from the Azure Portal (click **Shared access signature** under **Settings** in the Portal Storage account blade) or using the Azure CLI:

```bash
# Storage account - account-level SAS
az storage account generate-sas \
--account-name <storage-account-name> \
--services t \
--resource-types <resource-types> \
--permissions <permissions> \
--expiry <expiry-date>

# Storage account - table-level SAS
az storage table generate-sas \
--name <table-name>
```

## Key concepts

- **TableServiceClient** - A `TableServiceClient` is a client object that enables you to interact with the Table Service in order to create, list, and delete tables.
- **TableClient** - A `TableClient` is a client object that enables you to interact with a specific table in order to create, update, list, and delete entities within it.
- **Table** - A table is a collection of entities. Tables don't enforce a schema on entities, which means a single table can contain entities that have different sets of properties.
- **Entity** - An entity is a set of properties, similar to a database row. An entity in Azure Storage can be up to 1MB in size. An entity in Azure Cosmos DB can be up to 2MB in size. An entity has a partition key and a row key which together uniquely identify the entity within the table.
- **Properties** - A property is a name-value pair. Each entity can include up to 252 properties to store data. Each entity also has three system properties that specify a partition key, a row key, and a timestamp.
- **Partition Key** - An entity's partition key identifies the partition within the table to which the entity belongs. Entities with the same partition key can be queried more quickly, and inserted/updated in atomic operations.
- **Row Key** - An entity's row key is its unique identifier within a partition.

Common uses of the Table service include:

- Storing TBs of structured data capable of serving web scale applications
- Storing datasets that don't require complex joins, foreign keys, or stored procedures and can be de-normalized for fast access
- Quickly querying data using a clustered index
- Accessing data using the OData protocol

## Examples
Use the client library for Tables to:
- manages tables
- edit and access table contents

- [Authorize a client](#authorize-a-client)
- [Authorize with a connection string](#authorize-with-a-connection-string)
- [Authorize with a Shared Key credential](#authorize-with-a-shared-key-credential)
- [Authorize with a Shared Access Signature (SAS) token](#authorize-with-a-shared-access-signature-sas-token)
- [Create, List, and Delete Azure tables](#create-list-and-delete-azure-tables)
- [Construct a `TableServiceClient`](#construct-a-tableserviceclient)
- [Create a table](#create-a-table)
- [List tables](#list-tables)
- [Delete a table](#delete-a-table)
- [Create, List, and Delete table entities](##create-list-and-delete-table-entities)
- [Construct a `TableClient`](#construct-a-tableclient)
- [Create an entity](#create-an-entity)
- [List entities](#list-entities)
- [Delete an entity](#delete-an-entity)

### Authorize a client

#### Authorize with a connection string

To use a connection string to authorize your client, call the builder's `connectionString` method with your connection string.

```java
TableServiceClient tableServiceClient = new TableServiceClientBuilder()
.connectionString("<your-connection-string>")
.buildClient();
```

#### Authorize with a Shared Key credential

To use a Shared Key to authorize your client, create an instance of `TablesSharedKeyCredential` with your account name and access key. Call the builder's `endpoint` method with your account URL and the `credential` method with the `TablesSharedKeyCredential` object you created.

```java
TablesSharedKeyCredential credential = new TablesSharedKeyCredential("<your-account-name>", "<account-access-key>");
TableServiceClient tableServiceClient = new TableServiceClientBuilder()
.endpoint("<your-table-account-url>")
.credential(credential)
.buildClient();
```

#### Authorize with a Shared Access Signature (SAS) token

To use a SAS to authorize your client, call the builder's `endpoint` method with your account URL and the `sasToken` method with your SAS.

```java
TableServiceClient tableServiceClient = new TableServiceClientBuilder()
.endpoint("<your-table-account-url>")
.sasToken("<sas-token-string>")
.buildClient();
```

### Create, List, and Delete Azure tables

#### Construct a `TableServiceClient`

Construct a `TableServiceClient` by creating an instance of `TableServiceClientBuilder` and then calling the builder's `buildClient` or `buildAsyncClient` methods.

```java
TableServiceClient tableServiceClient = new TableServiceClientBuilder()
.connectionString("<your-connection-string>") // e.g.
.buildClient();
```

#### Create a table

Create a table by calling the `TableServiceClient`'s `createTable` method. An exception will be thrown if a table with the provided name exists.

```java
tableServiceClient.createTable(tableName);
```

Alternatively, you can call the `createTableIfNotExists` method which will create the table only if no such table exists, and does not throw an exception.

```java
tableServiceClient.createTableIfNotExists(tableName);
```

#### List tables

List or query the set of existing tables by calling the `TableServiceClient`'s `listTables` method, optionally passing in a `ListTablesOptions` instance to filter or limit the query results. See [Supported Query Options][query_options] for details about supported query options.

```java
ListTablesOptions options = new ListTablesOptions()
.setFilter(String.format("TableName eq '%s'", tableName));

for (TableItem tableItem : tableServiceClient.listTables(options)) {
System.out.println(tableItem.getName());
}
```

#### Delete a table

Delete a table by calling the `TableServiceClient`'s `deleteTable` method. An exception will be thrown if no table with the provided name exists.

```java
tableServiceClient.deleteTable(tableName);
```

### Create, List, and Delete table entities

#### Construct a `TableClient`

Construct a `TableClient` by creating an instance of `TableClientBuilder`, calling the builder's `tableName` method with the name of the table, and then calling its `buildClient` or `buildAsyncClient` methods.

```java
TableClient tableClient = new TableClientBuilder()
.connectionString("<your-connection-string>") // e.g.
.tableName(tableName)
.buildClient();
```

Alternatively, a `TableClient` can be retrieved from an existing `TableServiceClient` by calling its `getTableClient` method.

```java
TableClient tableClient = tableServiceClient.getTableClient(tableName);
```

#### Create an entity

Create a new `TableEntity` instance, providing the partition key and row key of the entity to create, optionally adding properties to the created object. Then pass the object to the `TableClient`'s `createEntity` method. An exception will be thrown if an entity with the provided partition key and row key exists within the table.

```java
TableEntity entity = new TableEntity(partitionKey, rowKey)
.addProperty("Product", "Marker Set")
.addProperty("Price", 5.00)
.addProperty("Quantity", 21);

tableClient.createEntity(entity);
```

Alternatively, you can call the `createEntityIfNotExists` method which will create the entity only if no entity with the provided partition key and row key exists within the table, and does not throw an exception.

```java
tableClient.createEntityIfNotExists(entity);
```

#### List entities

List or query the set of entities within the table by calling the `TableClient`'s `listEntities` method, optionally passing in a `ListEntitiesOptions` instance to filter, select, or limit the query results. See [Supported Query Options][query_options] for details about supported query options.

```java
ListEntitiesOptions options = new ListEntitiesOptions()
.setFilter(String.format("PartitionKey eq '%s'", partitionKey))
.setSelect("Product, Price");

for (TableEntity entity : tableClient.listEntities(options)) {
System.out.println(String.format("%s: %.2f", entity.getProperty("Product"), entity.getProperty("Price")));
}
```

#### Delete an entity

Delete an entity by calling the `TableClient`'s `deleteEntity` method. An exception will be thrown if no entity with the provided partition key and row key exists.

```java
tableClient.deleteEntity(partitionKey, rowKey);
```

## Troubleshooting

### General
When you interact with Tables service using the Azure Tables library for Java, errors returned by the service correspond to the same HTTP status codes returned for [REST API][rest_api] requests.

For example, if you try to create a table that already exists, a `409` error is returned, indicating "Conflict".

```java
// Create the table if it doesn't already exist.
tableServiceClient.createTableIfNotExists(tableName);

// Now attempt to create the same table unconditionally.
try {
tableServiceClient.createTable(tableName);
} catch (TableServiceErrorException e) {
System.out.println(e.getResponse().getStatusCode()); // 409
}
```

### Logging
Enabling logging may help uncover useful information about failures. In order to see a log of HTTP requests and responses, set the `AZURE_LOG_LEVEL` environment variable to the desired verbosity. See [LogLevel][log_level] for a description of available log levels.

## Next steps

Get started with our [Table samples][samples].

## Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a [Contributor License Agreement (CLA)][cla] declaring that you have the right to, and actually do, grant us the rights to use your contribution.
Expand All @@ -51,9 +327,17 @@ This project has adopted the [Microsoft Open Source Code of Conduct][coc]. For m
[coc_contact]: mailto:opencode@microsoft.com
[coc_faq]: https://opensource.microsoft.com/codeofconduct/faq/
[coc]: https://opensource.microsoft.com/codeofconduct/
[cosmosdb_create_cli]: https://docs.microsoft.com/en-us/azure/cosmos-db/scripts/cli/table/create
[cosmosdb_create_portal]: https://docs.microsoft.com/en-us/azure/cosmos-db/create-table-java#create-a-database-account
[jdk]: https://docs.microsoft.com/java/azure/jdk/
[log_level]: https://github.com/Azure/azure-sdk-for-java/blob/master/sdk/core/azure-core/src/main/java/com/azure/core/util/logging/LogLevel.java
[package]: https://search.maven.org/artifact/com.azure/azure-data-tables
[samples_readme]: src/samples/README.md
[product_documentation]: https://docs.microsoft.com/en-us/azure/cosmos-db/table-storage-overview
[query_options]: https://docs.microsoft.com/en-us/rest/api/storageservices/querying-tables-and-entities#supported-query-options
[rest_api]: https://docs.microsoft.com/en-us/rest/api/storageservices/table-service-rest-api
[samples]: src/samples/java/
[source_code]: src
[storage_account_create_cli]: https://docs.microsoft.com/en-us/azure/storage/common/storage-account-create?tabs=azure-cli
[storage_account_create_portal]: https://docs.microsoft.com/en-us/azure/storage/common/storage-account-create?tabs=azure-portal

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![Impressions](https://azure-sdk-impressions.azurewebsites.net/api/impressions/azure-sdk-for-java%2Fsdk%2Ftables%2Fazure-data-tables%2FREADME.png)

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