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title: "PolyBase T-SQL objects | Microsoft Docs"
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# PolyBase T-SQL objects
[!INCLUDE[tsql-appliesto-ss2016-xxxx-xxxx-xxx_md](../../includes/tsql-appliesto-ss2016-xxxx-xxxx-xxx-md.md)]

  To use  PolyBase, you must create external tables to reference your external data.  
  
 [CREATE DATABASE SCOPED CREDENTIAL (Transact-SQL)](../../t-sql/statements/create-database-scoped-credential-transact-sql.md)  
  
 [CREATE EXTERNAL DATA SOURCE (Transact-SQL)](../../t-sql/statements/create-external-data-source-transact-sql.md)  
  
 [CREATE EXTERNAL FILE FORMAT (Transact-SQL)](../../t-sql/statements/create-external-file-format-transact-sql.md)  
  
 [CREATE EXTERNAL TABLE (Transact-SQL)](../../t-sql/statements/create-external-table-transact-sql.md)  
  
 [CREATE STATISTICS (Transact-SQL)](../../t-sql/statements/create-statistics-transact-sql.md)  
  
## Prerequisites  
 Configure PolyBase. See [PolyBase configuration](../../relational-databases/polybase/polybase-configuration.md).  
  
## Create external tables for Hadoop  
 **1. Create Database Scoped Credential**  
  
 This step is required only for Kerberos-secured Hadoop clusters.  
  
```sql  
-- Create a master key on the database.  
-- Required to encrypt the credential secret.  
  
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'S0me!nfo';  
  
-- Create a database scoped credential  for Kerberos-secured Hadoop clusters.  
-- IDENTITY: the Kerberos user name.  
-- SECRET: the Kerberos password  
  
CREATE DATABASE SCOPED CREDENTIAL HadoopUser1   
WITH IDENTITY = '<hadoop_user_name>', Secret = '<hadoop_password>';  
  
```  
  
 **2. Create External Data Source**  
  
```sql  
-- Create an external data source.  
-- LOCATION (Required) : Hadoop Name Node IP address and port.  
-- RESOURCE MANAGER LOCATION (Optional): Hadoop Resource Manager location to enable pushdown computation.  
-- CREDENTIAL (Optional):  the database scoped credential, created above.  
  
CREATE EXTERNAL DATA SOURCE MyHadoopCluster WITH (  
        TYPE = HADOOP,   
        LOCATION ='hdfs://10.xxx.xx.xxx:xxxx',   
        RESOURCE_MANAGER_LOCATION = '10.xxx.xx.xxx:xxxx',   
        CREDENTIAL = HadoopUser1      
);  
  
```  
  
 **3. Create External File Format**  
  
```sql  
-- Create an external file format.  
-- FORMAT TYPE: Type of format in Hadoop (DELIMITEDTEXT,  RCFILE, ORC, PARQUET).  
  
CREATE EXTERNAL FILE FORMAT TextFileFormat WITH (  
        FORMAT_TYPE = DELIMITEDTEXT,   
        FORMAT_OPTIONS (FIELD_TERMINATOR ='|',   
                USE_TYPE_DEFAULT = TRUE)  
  
```  
  
 **4. Create External Table**  
  
```sql  
-- Create an external table pointing to data stored in Hadoop.  
-- LOCATION: path to file or directory that contains the data (relative to HDFS root).  
  
CREATE EXTERNAL TABLE [dbo].[CarSensor_Data] (  
        [SensorKey] int NOT NULL,   
        [CustomerKey] int NOT NULL,   
        [GeographyKey] int NULL,   
        [Speed] float NOT NULL,   
        [YearMeasured] int NOT NULL  
)  
WITH (LOCATION='/Demo/',   
        DATA_SOURCE = MyHadoopCluster,  
        FILE_FORMAT = TextFileFormat  
);  
  
```  
  
 **5. Create Statistics**  
  
```sql  
-- Create statistics on an external table.   
CREATE STATISTICS StatsForSensors on CarSensor_Data(CustomerKey, Speed)  
  
```  
  
## Create external tables for Azure blob storage  
 **1. Create Database Scoped Credential**  
  
```sql  
-- Create a master key on the database.  
-- Required to encrypt the credential secret.  
  
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'S0me!nfo';  
  
-- Create a database scoped credential  for Azure blob storage.  
-- IDENTITY: any string (this is not used for authentication to Azure storage).  
-- SECRET: your Azure storage account key.  
  
CREATE DATABASE SCOPED CREDENTIAL AzureStorageCredential   
WITH IDENTITY = 'user', Secret = '<azure_storage_account_key>';  
  
```  
  
 **2. Create External Data Source**  
  
```sql  
-- Create an external data source.  
-- LOCATION:  Azure account storage account name and blob container name.  
-- CREDENTIAL: The database scoped credential created above.  
  
CREATE EXTERNAL DATA SOURCE AzureStorage with (  
        TYPE = HADOOP,   
        LOCATION ='wasbs://<blob_container_name>@<azure_storage_account_name>.blob.core.windows.net',  
        CREDENTIAL = AzureStorageCredential  
);  
  
```  
  
 **3. Create External File Format**  
  
```sql  
-- Create an external file format.  
-- FORMAT TYPE: Type of format in Hadoop (DELIMITEDTEXT,  RCFILE, ORC, PARQUET).  
  
CREATE EXTERNAL FILE FORMAT TextFileFormat WITH (  
        FORMAT_TYPE = DELIMITEDTEXT,   
        FORMAT_OPTIONS (FIELD_TERMINATOR ='|',   
                USE_TYPE_DEFAULT = TRUE)  
  
```  
  
 **4. Create External Table**  
  
```sql  
-- Create an external table pointing to data stored in Azure storage.  
-- LOCATION: path to a file or directory that contains the data (relative to the blob container).  
-- To point to all files under the blob container, use LOCATION='/'   
  
CREATE EXTERNAL TABLE [dbo].[CarSensor_Data] (  
        [SensorKey] int NOT NULL,   
        [CustomerKey] int NOT NULL,   
        [GeographyKey] int NULL,   
        [Speed] float NOT NULL,   
        [YearMeasured] int NOT NULL  
)  
WITH (LOCATION='/Demo/',   
        DATA_SOURCE = AzureStorage,  
        FILE_FORMAT = TextFileFormat  
);  
  
```  
  
 **5. Create Statistics**  
  
```sql  
-- Create statistics on an external table.   
CREATE STATISTICS StatsForSensors on CarSensor_Data(CustomerKey, Speed)  
  
```  
 
## Create external tables for Azure Data Lake Store
Azure Data Lake Store is only supported by PolyBase in SQL Data Warehouse.
 For more information about Azure SQL Data Warhouse and ADLS, go to [Load with Azure Data Lake Store](https://docs.microsoft.com/en-us/azure/sql-data-warehouse/sql-data-warehouse-load-from-azure-data-lake-store)
 
 **1. Create Database Scoped Credential**  
  

```sql
-- Create a Database Master Key.
-- Only necessary if one does not already exist.
-- Required to encrypt the credential secret in the next step.

CREATE MASTER KEY;

-- Create a database scoped credential
-- IDENTITY: Pass the client id and OAuth 2.0 Token Endpoint taken from your Azure Active Directory Application
-- SECRET: Provide your AAD Application Service Principal key.
-- For more information on Create Database Scoped Credential: https://msdn.microsoft.com/en-us/library/mt270260.aspx

CREATE DATABASE SCOPED CREDENTIAL ADL_User
WITH
    IDENTITY = '<client_id>@<OAuth_2.0_Token_EndPoint>'
    ,SECRET = '<key>'
;
```  
  
 **2. Create External Data Source**  
  
```sql  
-- TYPE: HADOOP - PolyBase uses Hadoop APIs to access data in Azure Data Lake Store.
-- LOCATION: Provide Azure storage account name and blob container name.
-- CREDENTIAL: Provide the credential created in the previous step.

CREATE EXTERNAL DATA SOURCE AzureDataLakeStore
WITH (
    TYPE = HADOOP,
    LOCATION = 'adl://<AzureDataLake account_name>.azuredatalake.net,
    CREDENTIAL = AzureStorageCredential
);
```  
  
 **3. Create External File Format**  
  
```sql  
-- FIELD_TERMINATOR: Marks the end of each field (column) in a delimited text file
-- STRING_DELIMITER: Specifies the field terminator for data of type string in the text-delimited file.
-- DATE_FORMAT: Specifies a custom format for all date and time data that might appear in a delimited text file.
-- Use_Type_Default: Store all Missing values as NULL

CREATE EXTERNAL FILE FORMAT TextFileFormat
WITH
(   FORMAT_TYPE = DELIMITEDTEXT
,    FORMAT_OPTIONS    (   FIELD_TERMINATOR = '|'
                    ,    STRING_DELIMITER = ''
                    ,    DATE_FORMAT         = 'yyyy-MM-dd HH:mm:ss.fff'
                    ,    USE_TYPE_DEFAULT = FALSE
                    )
);
```  
  
 **4. Create External Table**  
  
```sql  
-- LOCATION: Folder under the ADLS root folder.
-- DATA_SOURCE: Specifies which Data Source Object to use.
-- FILE_FORMAT: Specifies which File Format Object to use
-- REJECT_TYPE: Specifies how you want to deal with rejected rows. Either Value or percentage of the total
-- REJECT_VALUE: Sets the Reject value based on the reject type.

-- DimProduct
CREATE EXTERNAL TABLE [dbo].[DimProduct_external] (
    [ProductKey] [int] NOT NULL,
    [ProductLabel] [nvarchar](255) NULL,
    [ProductName] [nvarchar](500) NULL
)
WITH
(
    LOCATION='/DimProduct/'
,   DATA_SOURCE = AzureDataLakeStore
,   FILE_FORMAT = TextFileFormat
,   REJECT_TYPE = VALUE
,   REJECT_VALUE = 0
)
;
```  
  
 **5. Create Statistics**  
  
```sql     
CREATE STATISTICS StatsForProduct on DimProduct_external(ProductKey)  
```  

## Next steps  
 For examples of queries, see [PolyBase Queries](../../relational-databases/polybase/polybase-queries.md).  
  
## See Also  
 [Get started with PolyBase](../../relational-databases/polybase/get-started-with-polybase.md)   
 [PolyBase Guide](../../relational-databases/polybase/polybase-guide.md)