MySQL按顺序查找每组的最近/最大记录，以及如何最小化/缩短此查询以及每次它返回组的第一行值时，而我喜欢选择组的最后一行值，并根据 ja.id 对值进行排序？我知道这是一个糟糕的查询，任何人都可以建议或为我提供解决方案来缩短此查询。我已在所有表中使用了所有必要的列索引。 如何在不使用 union all 的情况下缩短查询。union all 中的查询与 where 语句中的查询相同。
SELECT
a.previous_status,
a.rejected_status,
a.rejection_reason_text,
a.rejection_reason,
a.rjaId,
a.refer_applied_status,
a.title,
a.playerId,
a.gameId,
a.gamePostDate,
a.game_referal_amount,
a.country,
a.country_name,
a.state,
a.location,
a.state_abb,
a.game_type,
a.appliedId,
a.appliedStatus,
a.admin_review,
a.is_req_referal_check,
a.memberId,
a.appliedEmail,
a.game_id,
a.referred_id,
a.memStateAbb,
a.memState,
a.memZipcode,
a.memCity,
a.memCountryNme,
a.memCountry,
a.appliedMemberName,
a.first_name,
a.primary_contact,
a.last_name,
a.addressbookImage,
a.userImage,
a.last_login,
a.user_experience_year,
a.user_experience_month,
a.current_designation,
a.current_player,
a.appliedDate,
a.addressbook_id,
a.joiningdate,
a.gameStatus,
a.gameReferalAmountType,
a.gameFreezeStatus,
a.gameFreezeMsg,
a.app_assign_back_to_rp_count,
a.applied_source,
a.max_id,
a.gamesApplied,
a.gamesAppliedId,
SUM(a.totalgameApplied) AS totalgameApplied,
a.application_assign_to_rp_status,
a.rpAppliedSource,
a.applied_on
FROM
(
(
SELECT
ja.previous_status,
ja.rejected_status,
ja.rejection_reason_text,
ja.rejection_reason,
rja.id AS rjaId,
rja. STATUS AS refer_applied_status,
jp.title,
jp.user_user_id AS playerId,
jp.id AS gameId,
jp.posted_on AS gamePostDate,
jp.game_referal_amount,
jp.country,
jp.country_name,
jp.state,
jp.location,
jp.state_abb,
jp.game_type,
ja.id AS appliedId,
IFNULL(ja. STATUS, '') AS appliedStatus,
IFNULL(ja.admin_review, '') AS admin_review,
ja.is_req_referal_check,
usr.id AS memberId,
rja.email AS appliedEmail,
rja.game_id,
rja.referred_id,
mem.state_abb AS memStateAbb,
mem.state AS memState,
mem.zipcode AS memZipcode,
mem.city AS memCity,
mem.country_name AS memCountryNme,
mem.country_code AS memCountry,
usc. NAME AS appliedMemberName,
usc.first_name,
IFNULL(
mem.primary_contact,
usc.phone_number
) AS primary_contact,
usc.last_name,
usc.profileimage_path AS addressbookImage,
usr.profile_image AS userImage,
usr.last_login,
mem.user_experience_year,
mem.user_experience_month,
mem.current_designation,
mem.current_player,
rja.create_date AS appliedDate,
rja.addressbook_id,
IFNULL(ja.joining_date, '') AS joiningdate,
jp. STATUS AS gameStatus,
jp.games_referal_amount_type AS gameReferalAmountType,
jp.game_freeze_status AS gameFreezeStatus,
jp.game_freeze_message AS gameFreezeMsg,
ja.app_assign_back_to_rp_count,
ja.applied_source,
MAX(rja.id) AS max_id,
GROUP_CONCAT(
jp.title
ORDER BY
rja.create_date DESC
) AS gamesApplied,
GROUP_CONCAT(DISTINCT(jp.id)) AS gamesAppliedId,
COUNT(DISTINCT(jp.id)) totalgameApplied,
ja.application_assign_to_rp_status,
1 AS rpAppliedSource,
rja.create_date AS applied_on
FROM
(`refer_gameapplied` AS rja)
JOIN `games_post` AS jp ON `jp`.`id` = `rja`.`game_id`
JOIN `user_socialconnections` AS usc ON `rja`.`addressbook_id` = `usc`.`id`
LEFT JOIN `user_user` AS usr ON `usr`.`email` = `rja`.`email`
LEFT JOIN `user_member` AS mem ON `mem`.`user_id` = `usr`.`id`
LEFT JOIN `game_applied` AS ja ON `ja`.`id` = `rja`.`applied_id`
WHERE
`rja`.`referby_id` = '2389'
GROUP BY
`rja`.`email`
)
UNION ALL
(
SELECT
ja.previous_status,
ja.rejected_status,
ja.rejection_reason_text,
ja.rejection_reason,
jr.id AS rjaId,
jrtm. STATUS AS refer_applied_status,
jp.title,
jp.user_user_id AS playerId,
jp.id AS gameId,
jp.posted_on AS gamePostDate,
jp.game_referal_amount,
jp.country,
jp.country_name,
jp.state,
jp.location,
jp.state_abb,
jp.game_type,
ja.id AS appliedId,
IFNULL(ja. STATUS, '') AS appliedStatus,
IFNULL(ja.admin_review, '') AS admin_review,
ja.is_req_referal_check,
usr.id AS memberId,
jrtm.referto_email AS refappliedEmail,
jr.game_id,
jrtm.id,
mem.state_abb AS memStateAbb,
mem.state AS memState,
mem.zipcode AS memZipcode,
mem.city AS memCity,
mem.country_name AS memCountryNme,
mem.country_code AS memCountry,
usc. NAME AS appliedMemberName,
usc.first_name,
IFNULL(
mem.primary_contact,
usc.phone_number
) AS primary_contact,
usc.last_name,
usc.profileimage_path AS addressbookImage,
usr.profile_image AS userImage,
usr.last_login,
mem.user_experience_year,
mem.user_experience_month,
mem.current_designation,
mem.current_player,
jrtm.refer_on AS appliedDate,
jrtm.referto_addressbookid,
IFNULL(ja.joining_date, '') AS joiningdate,
jp. STATUS AS gameStatus,
jp.games_referal_amount_type AS gameReferalAmountType,
jp.game_freeze_status AS gameFreezeStatus,
jp.game_freeze_message AS gameFreezeMsg,
ja.app_assign_back_to_rp_count,
ja.applied_source,
MAX(jrtm.id) AS max_id,
GROUP_CONCAT(
jp.title
ORDER BY
jr.refer_on DESC
) AS gamesApplied,
GROUP_CONCAT(DISTINCT(jp.id)) AS gamesAppliedId,
COUNT(DISTINCT(jp.id)) totalgameApplied,
ja.application_assign_to_rp_status,
2 AS rpAppliedSource,
jrtm.refer_on AS applied_on
FROM
(`game_refer` AS jr)
JOIN `game_refer_to_member` AS jrtm ON `jrtm`.`rid` = `jr`.`id`
JOIN `games_post` AS jp ON `jp`.`id` = `jr`.`game_id`
JOIN `user_socialconnections` AS usc ON `jrtm`.`referto_addressbookid` = `usc`.`id`
LEFT JOIN `user_user` AS usr ON `usr`.`email` = `jrtm`.`referto_email`
LEFT JOIN `user_member` AS mem ON `mem`.`user_id` = `usr`.`id`
LEFT JOIN `game_applied` AS ja ON `ja`.`referred_by` = `jrtm`.`id`
WHERE
`jrtm`.`status` = '1'
AND `jr`.`referby_user_id` = '2389'
AND `jrtm`.`refer_source` NOT IN ('4')
GROUP BY
`jrtm`.`referto_email`
)
) a
GROUP BY
a.appliedEmail
ORDER BY
a.gamesAppliedId DESC
最佳答案
这听起来像是一个“groupwise-max”问题。我添加了一个您应该研究的标签。
至少去掉与问题无关的列。
尝试折腾除 jrtm 和 jr 之外的表，看看性能问题是否仍然存在。 (我认为LEFT JOIN可能是转移注意力。)
尝试使用 UNION 的一部分，然后使用另一部分。这可以确定两者中哪一个负担更大。
要添加的一些索引:
rja: (referby_id, create_date)
jrtm: (status, referto_email)
jrtm: (rid, status, referto_email)
jr: (referby_user_id, refer_on)
DISTINCT 不是函数。不要在 DISTINCT(jp.id) 中使用父项。
关于MySQL 按顺序查找每组最近/最大记录，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49534239/