Box 1: CREATE EXTERNAL TABLE An external table points to data located in Hadoop, Azure Storage blob, or AzureDataLakeStorage. External tables are used to read data from files or write data to files in Azure Storage. With SynapseSQL, you can use external tables to read external data using dedicated SQL pool or serverless SQL pool. Syntax: CREATE EXTERNAL TABLE { database_name.schema_name.table_name | schema_name.table_name | table_name } ( <column_definition> [ ,...n ] ) WITH ( LOCATION = 'folder_or_filepath', DATA_SOURCE = external_data_source_name, FILE_FORMAT = external_file_format_name Box 2. OPENROWSET When using serverless SQL pool, CETAS is used to create an external table and export query results to Azure Storage Blob or Azure Data Lake Storage Gen2. Exam ple: AS SELECT decennialTime, stateName, SUM(population) AS population FROM OPENROWSET(BULK 'https://azureopendatastorage.blob.core.windows.net/censusdatacontainer/release/us_population_county/year=*/*.parquet', FORMAT='PARQUET') AS [r] GROUP BY decennialTime, stateName GO Reference: https://docs.microsoft.com/en-us/azure/synapse-analytics/sql/develop-tables-external-tables
Box 1: CREATE EXTERNAL TABLE
An external table points to data located in Hadoop, Azure Storage blob, or AzureDataLakeStorage. External tables are used to read data from files or write data to files in Azure Storage. With SynapseSQL, you can use external tables to read external data using dedicated SQL pool or serverless SQL pool.
Syntax:
CREATE EXTERNAL TABLE { database_name.schema_name.table_name | schema_name.table_name | table_name }
( <column_definition> [ ,...n ] )
WITH (
LOCATION = 'folder_or_filepath', DATA_SOURCE
= external_data_source_name, FILE_FORMAT =
external_file_format_name
Box 2. OPENROWSET
When using serverless SQL pool, CETAS is used to create an external table and export query results to Azure Storage Blob or Azure Data Lake Storage Gen2.
Exam
ple:
AS
SELECT decennialTime, stateName, SUM(population) AS population FROM
OPENROWSET(BULK 'https://azureopendatastorage.blob.core.windows.net/censusdatacontainer/release/us_population_county/year=*/*.parquet',
FORMAT='PARQUET') AS [r]
GROUP BY decennialTime, stateName
GO
Reference:
https://docs.microsoft.com/en-us/azure/synapse-analytics/sql/develop-tables-external-tables