Fix and tests for issue #69

source/shared/core_results.cpp

@@ -1351,6 +1351,12 @@ SQLRETURN sqlsrv_buffered_result_set::wide_to_system_string( SQLSMALLINT field_i
             field_data = &row[ meta[ field_index ].offset ] + sizeof( SQLULEN ) + read_so_far;
         }
 
+        if (field_len == 0) // empty string, no need for conversion
+        {
+            *out_buffer_length = 0;
+            return SQL_SUCCESS;
+        }
+
         // allocate enough to handle WC -> DBCS conversion if it happens
         temp_string = reinterpret_cast<SQLCHAR*>( sqlsrv_malloc( field_len, sizeof(char), sizeof(char)));
 			

test/pdo_sqlsrv/pdo_069_fetch_empty_nvarchar_buffered.phpt

@@ -0,0 +1,38 @@
+--TEST--
+GitHub issue #69 - fetching an empty nvarchar using client buffer
+--SKIPIF--
+--FILE--
+<?php
+// Connect 
+require_once("autonomous_setup.php");
+
+$conn = new PDO("sqlsrv:server=$serverName", $username, $password);   
+$conn->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );   
+    
+$sql = "EXEC dbo.sp_executesql 
+N'DECLARE @x nvarchar(max)
+SET @x = '''' -- empty string
+SELECT @x AS [Empty_Nvarchar_Max]'";
+
+$stmt = $conn->prepare($sql, array(PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL, PDO::SQLSRV_ATTR_CURSOR_SCROLL_TYPE => PDO::SQLSRV_CURSOR_BUFFERED));  
+$stmt->execute();
+
+$return = $stmt->fetchAll( PDO::FETCH_ASSOC ); 
+print_r($return);
+
+// Free the statement and connection resources. 
+$stmt = null;  
+$conn = null;    
+
+print "Done";
+?> 
+--EXPECT--
+Array
+(
+    [0] => Array
+        (
+            [Empty_Nvarchar_Max] => 
+        )
+
+)
+Done

test/sqlsrv/srv_069_fetch_empty_nvarchar_buffered.phpt

@@ -0,0 +1,44 @@
+--TEST--
+GitHub issue #69 - fetching an empty nvarchar using client buffer
+--SKIPIF--
+--FILE--
+<?php
+function print_errors()
+{
+    die( print_r( sqlsrv_errors(), true));
+}
+
+function test()
+{
+    require_once("autonomous_setup.php");
+
+    // Connect
+    $conn = sqlsrv_connect($serverName, $connectionInfo);
+    if( !$conn ) { print_errors(); }
+        
+    $sql = "EXEC dbo.sp_executesql 
+    N'DECLARE @x nvarchar(max)
+    SET @x = '''' -- empty string
+    SELECT @x AS [Empty_Nvarchar_Max]'";
+    
+    $stmt = sqlsrv_query($conn, $sql, [], ["Scrollable" => 'buffered']);
+    if (! $stmt) { print_errors(); }
+
+    $return = sqlsrv_fetch_array($stmt, SQLSRV_FETCH_ASSOC); 
+    print_r($return);
+   
+    // Free the statement and connection resources. 
+    sqlsrv_free_stmt( $stmt);  
+    sqlsrv_close( $conn);    
+}
+    
+test();
+
+print "Done";    
+?> 
+--EXPECT--
+Array
+(
+    [Empty_Nvarchar_Max] => 
+)
+Done