mysql 子查询 例子

子查询

也就是嵌套查询
例如 select * from (select * from table) AS 别名

SELECT *, successCount/(failCount+successCount+warnCount) as successRate
FROM (
      SELECT
			MAX(l.id) AS id,
			t.task_code AS taskCode,
			t.task_name AS taskName,
			MAX(l.batch_id) AS batchId,
			MAX(l.end_date_time) AS lastExecuteTime,
			l.execute_status AS executeStatus,
			SUM( CASE WHEN l.execute_status = '1' THEN 1 ELSE 0 END ) AS successCount,
			SUM( CASE WHEN l.execute_status = '0' THEN 1 ELSE 0 END ) AS failCount,
			SUM( CASE WHEN l.execute_status = '2' THEN 1 ELSE 0 END ) AS warnCount
		FROM
			qrtz_task_log l
		INNER JOIN qrtz_task t ON l.task_code = t.task_code AND t.delete_flag=0
		WHERE l.delete_flag=0
				AND l.execute_date >= "2021-01-01"
				AND l.execute_date <= "2021-02-01"
		GROUP BY l.task_code ) emp  
		ORDER BY IFNULL(successCount/(failCount+successCount+warnCount), 0)