2 files changed, 43 insertions, 1 deletions
diff --git a/phpBB/phpbb/db/tools/mssql.php b/phpBB/phpbb/db/tools/mssql.php
index 6f800f730d..0dfb09b1ba 100644
--- a/phpBB/phpbb/db/tools/mssql.php
+++ b/phpBB/phpbb/db/tools/mssql.php
@@ -448,6 +448,10 @@ class mssql extends tools
 			}
 		}
 
+		// Drop primary keys depending on this column
+		$result = $this->mssql_get_drop_default_primary_key_queries($table_name, $column_name);
+		$statements = array_merge($statements, $result);
+
 		// Drop default value constraint
 		$result = $this->mssql_get_drop_default_constraints_queries($table_name, $column_name);
 		$statements = array_merge($statements, $result);
@@ -685,6 +689,37 @@ class mssql extends tools
 	}
 
 	/**
+	 * Get queries to drop the primary keys depending on the specified column
+	 *
+	 * We need to drop primary keys depending on this column before being able
+	 * to delete them.
+	 *
+	 * @param string $table_name
+	 * @param string $column_name
+	 * @return array		Array with SQL statements
+	 */
+	protected function mssql_get_drop_default_primary_key_queries($table_name, $column_name)
+	{
+		$statements = array();
+
+		$sql = "SELECT ccu.CONSTRAINT_NAME, ccu.COLUMN_NAME
+			FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc
+				JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE ccu ON tc.CONSTRAINT_NAME = ccu.Constraint_name
+			WHERE tc.TABLE_NAME = '{$table_name}'
+				AND tc.CONSTRAINT_TYPE = 'Primary Key'";
+
+		$result = $this->db->sql_query($sql);
+
+		while ($primary_key = $this->db->sql_fetchrow($result))
+		{
+			$statements[] = 'ALTER TABLE [' . $table_name . '] DROP CONSTRAINT [' . $primary_key['CONSTRAINT_NAME'] . ']';
+		}
+		$this->db->sql_freeresult($result);
+
+		return $statements;
+	}
+
+	/**
 	 * Checks to see if column is an identity column
 	 *
 	 * Identity columns cannot have defaults set for them.
diff --git a/tests/dbal/db_tools_test.php b/tests/dbal/db_tools_test.php
index f9243e7266..f78cebdec7 100644
--- a/tests/dbal/db_tools_test.php
+++ b/tests/dbal/db_tools_test.php
@@ -203,8 +203,15 @@ class phpbb_dbal_db_tools_test extends phpbb_database_test_case
 
 	public function test_list_columns()
 	{
+		$config = $this->get_database_config();
+		$table_columns = $this->table_data['COLUMNS'];
+
+		if (strpos($config['dbms'], 'mssql') !== false)
+		{
+			ksort($table_columns);
+		}
 		$this->assertEquals(
-			array_keys($this->table_data['COLUMNS']),
+			array_keys($table_columns),
 			array_values($this->tools->sql_list_columns('prefix_table_name'))
 		);
 	}