使用SQL语言中的DATE_FORMAT函数将日期转化为年月的形式，并使用LEFT JOIN语句将数据集与包含所有月份和年份的查询结果集连接起来，最后使用COALESCE函数将缺失值转化为0。

示例代码：

SELECT CONCAT(YEAR(date_column), '-', LPAD(MONTH(date_column), 2, '0')) AS year_month, COUNT(*) AS count FROM table_name GROUP BY year_month

改写后的代码：

SELECT CONCAT(y.year, '-', LPAD(m.month, 2, '0')) AS year_month, COALESCE(t.count, 0) AS count FROM (SELECT DISTINCT YEAR(date_column) AS year FROM table_name) y CROSS JOIN (SELECT DISTINCT MONTH(date_column) AS month FROM table_name) m LEFT JOIN (SELECT CONCAT(YEAR(date_column), '-', LPAD(MONTH(date_column), 2, '0')) AS year_month, COUNT(*) AS count FROM table_name GROUP BY year_month) t ON CONCAT(y.year, '-', LPAD(m.month, 2, '0')) = t.year_month ORDER BY year_month ASC;