有如下一条SQL 执行时间1.477s

 
SELECT 
  `c`.*,
  `p`.`patient_name`,
  `p`.`age_first_val` AS `age`,
  `p`.`patient_phone`,
  `p`.`department_name`,
  `p`.`case_type`,
  `p`.`check_time`,
  `p`.`card_no`,
  `p`.`doctor`,
  `p`.`outpatient`,
  `p`.`coll_time`,
  `r`.`json_data`,
  `r`.`report_form`,
  `p`.`created_at` AS `receive_time`,
  `r`.`created_at` AS `report_time`,
  `r`.`state` 
FROM
  `ts_report_card` AS `c` 
  LEFT JOIN `kd_report_spec` AS `r` 
    ON `r`.`ts_id` = `c`.`uuid`
  LEFT JOIN `sp_case_info` AS `p` 
    ON `p`.`uuid` = `r`.`case_id` 
where `r`.`state` = 1 
ORDER BY `c`.`created_at` DESC 
LIMIT 10 OFFSET 0;

优化后这条SQL执行时间0s

SELECT 
  `c`.*,
  `p`.`patient_name`,
  `p`.`age_first_val` AS `age`,
  `p`.`patient_phone`,
  `p`.`department_name`,
  `p`.`case_type`,
  `p`.`check_time`,
  `p`.`card_no`,
  `p`.`doctor`,
  `p`.`outpatient`,
  `p`.`coll_time`,
  `r`.`json_data`,
  `r`.`report_form`,
  `p`.`created_at` AS `receive_time`,
  `r`.`created_at` AS `report_time`,
  `r`.`state` 
FROM
  `ts_report_card` AS `c` 
  LEFT JOIN `kd_report_spec` AS `r` 
    ON `r`.`ts_id` = `c`.`uuid` AND r.state = 1
  LEFT JOIN `sp_case_info` AS `p` 
    ON `p`.`uuid` = `r`.`case_id` 
ORDER BY `c`.`created_at` DESC 
LIMIT 10 OFFSET 0;