db: added insert_id()

Database::insert_id() retrieves the auto-generated ID from the last INSERT
or UPDATE on a table containing an AUTO_INCREMENT column.

Change-Id: I6ec94d1820bb7e77bd37df33145caa93016fd328

src/core/util/Database.cc

@@ -73,6 +73,10 @@ my_ulonglong Database::affected_rows()
 	return mysql_affected_rows(handle);
 }
 
+my_ulonglong Database::insert_id()
+{
+	return mysql_insert_id(handle);
+}
 
 std::vector<Database::Variant> Database::get_variants(const std::string &variant, const std::string &benchmark) {
 	std::vector<Variant> result;

src/core/util/Database.hpp

@@ -85,6 +85,11 @@ namespace fail {
 		 */
 		my_ulonglong affected_rows();
 
+		/**
+		 * AUTO_INCREMENT id from the last INSERT or UPDATE statement.
+		 */
+		my_ulonglong insert_id();
+
 		/**
 		 * Interface to the util/CommandLine.hpp interface. In you
 		 * application you first call cmdline_setup(), which adds