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How to: Retrieve Binary Data as a Stream Using the SQLSRV Driver

Retrieving data as a stream is only available in the SQLSRV driver of the Microsoft Drivers for PHP for SQL Server, and is not available in the PDO_SQLSRV driver.

The Microsoft Drivers for PHP for SQL Server takes advantage of PHP streams for retrieving large amounts of binary data from the server. This topic demonstrates how to retrieve binary data as a stream.

Using the streams to retrieve binary data, such as images, avoids using large amounts of script memory by retrieving chunks of data instead of loading the whole object into script memory.

The following example retrieves binary data, an image in this case, from the Production.ProductPhoto table of the AdventureWorks database. The image is retrieved as a stream and displayed in the browser.

Retrieving image data as a stream is accomplished by using sqlsrv_fetch and sqlsrv_get_field with the return type specified as a binary stream. The return type is specified by using the constant SQLSRV_PHPTYPE_STREAM. For information about sqlsrv constants, see Constants (Microsoft Drivers for PHP for SQL Server).

The example assumes that SQL Server and the AdventureWorks database are installed on the local computer. All output is written to the browser when the example is run from the browser.

/* Connect to the local server using Windows Authentication and
specify the AdventureWorks database as the database in use. */
$serverName = "(local)";
$connectionInfo = array( "Database"=>"AdventureWorks");
$conn = sqlsrv_connect( $serverName, $connectionInfo);
if( $conn === false )
     echo "Could not connect.\n";
     die( print_r( sqlsrv_errors(), true));

/* Set up the Transact-SQL query. */
$tsql = "SELECT LargePhoto 
         FROM Production.ProductPhoto 
         WHERE ProductPhotoID = ?";

/* Set the parameter values and put them in an array. */
$productPhotoID = 70;
$params = array( $productPhotoID);

/* Execute the query. */
$stmt = sqlsrv_query($conn, $tsql, $params);
if( $stmt === false )
     echo "Error in statement execution.</br>";
     die( print_r( sqlsrv_errors(), true));

/* Retrieve and display the data.
The return data is retrieved as a binary stream. */
if ( sqlsrv_fetch( $stmt ) )
   $image = sqlsrv_get_field( $stmt, 0, 
   header("Content-Type: image/jpg");
     echo "Error in retrieving data.</br>";
     die(print_r( sqlsrv_errors(), true));

/* Free statement and connection resources. */
sqlsrv_free_stmt( $stmt);
sqlsrv_close( $conn);

Specifying the return type in the example demonstrates how to specify the PHP return type as a binary stream. Technically, it is not required in the example because the LargePhoto field has SQL Server type varbinary(max) and is therefore returned as a binary stream by default. For information about default PHP data types, see Default PHP Data Types. For information about how to specify PHP return types, see How to: Specify PHP Data Types.

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