[英]Use Select data in nested Select statement in MySQL
我在 MySQL 中有一个查询。
完整查询
SELECT
tc.expense AS expense,
tc.tour_sub_code,
tc.login_id
FROM
tc_wallet tc
WHERE tc.login_id = 'vinod.kumbala'
AND tc.expense = 'Daily Allowance'
AND tc.delete_flag = 'F'
AND tc.status != 'reject'
结果
Expense Tour_sub_code login_id
DAILY ALLOWANCE MOS-EUROPE100119 vinod.kumbala
DAILY ALLOWANCE Test vinod.kumbala
最初我从tc_wallet
表中获取数据。
现在我的要求是我需要找到特定tour_sub_code
的总出席人数。 出勤次数可以从attendance_master
该特定tour_sub_code
attendance_master
表中tour_sub_code
。 所以我包含了一个嵌套的选择查询,它是
嵌套选择
(SELECT
COUNT(*)
FROM
(SELECT
*
FROM
`attendance_master`
WHERE `delete_flag` = 'F'
AND login_id = 'vinod.kumbala'
AND `tour_sub_code` = tc.`tour_sub_code`
GROUP BY `device_date`) t1) AS newNoOfdays
完整查询
SELECT
tc.expense AS expense,
tc.tour_sub_code,
tc.login_id,
(SELECT
COUNT(*)
FROM
(SELECT
*
FROM
`attendance_master`
WHERE `delete_flag` = 'F'
AND login_id = 'vinod.kumbala'
AND `tour_sub_code` = tc.`tour_sub_code`
GROUP BY `device_date`) t1) AS newNoOfdays
FROM
tc_wallet tc
WHERE tc.login_id = 'vinod.kumbala'
AND tc.expense = 'Daily Allowance'
AND tc.delete_flag = 'F'
AND tc.status != 'reject'
现在这个查询给了我错误
“where 子句”中的未知列“tc.tour_sub_code”
预期结果
Expense Tour_sub_code login_id Count
DAILY ALLOWANCE MOS-EUROPE100119 vinod.kumbala 20
DAILY ALLOWANCE Test vinod.kumbala 44
我能知道我哪里出错了吗?
还有其他方法可以通过使用 JOINS 获得结果吗?
在最内层的子查询中,您引用的是最外层查询中的一列。 这对于 FROM 子句(派生表)中的子查询是不允许的。 但是 - 您不需要该子查询。 你需要的是COUNT(DISTINCT device_date)
改写
(SELECT
COUNT(*)
FROM
(SELECT
*
FROM
`attendance_master`
WHERE `delete_flag` = 'F'
AND login_id = 'vinod.kumbala'
AND `tour_sub_code` = tc.`tour_sub_code`
GROUP BY `device_date`) t1) AS newNoOfdays
到
(SELECT
COUNT(DISTINCT device_date)
FROM `attendance_master`
WHERE `delete_flag` = 'F'
AND login_id = 'vinod.kumbala'
AND `tour_sub_code` = tc.`tour_sub_code`
) AS newNoOfdays
您还可以将完整查询重写为 LEFT JOIN 查询:
SELECT
tc.expense AS expense,
tc.tour_sub_code,
tc.login_id,
COUNT(DISTINCT device_date) AS newNoOfdays
FROM tc_wallet tc
LEFT JOIN attendance_master am
ON am.tour_sub_code = tc.tour_sub_code
AND am.delete_flag = 'F'
AND am.login_id = 'vinod.kumbala'
WHERE tc.login_id = 'vinod.kumbala'
AND tc.expense = 'Daily Allowance'
AND tc.delete_flag = 'F'
AND tc.status != 'reject'
尝试这个:
SELECT
tc.expense AS expense,
tc.tour_sub_code,
tc.login_id,
count(*) as count
FROM
tc_wallet tc
INNER JOIN
attendance_master am
ON
tc.tour_sub_code = am.tour_sub_code AND
tc.login_id = am.login_id
WHERE tc.login_id = 'vinod.kumbala'
AND tc.expense = 'Daily Allowance'
AND tc.delete_flag = 'F'
AND tc.status != 'reject'
GROUP BY
tc.expense AS expense,
tc.tour_sub_code,
tc.login_id
尝试这个 - -
SELECT
tc.expense AS expense,
tc.tour_sub_code,
tc.login_id,
(SELECT
COUNT(am.*)
FROM `attendance_master` as am
WHERE am.delete_flag = 'F'
AND am.login_id = 'vinod.kumbala'
AND am.tour_sub_code = tc.tour_sub_code
GROUP BY am.device_date) AS count
FROM
tc_wallet tc
WHERE tc.login_id = 'vinod.kumbala'
AND tc.expense = 'Daily Allowance'
AND tc.delete_flag = 'F'
AND tc.status != 'reject'
你能试试这个吗:
select tc.expense AS expense,
tc.tour_sub_code,
tc.login_id,
newNoOfdays.countVal
from tc_wallet tc
inner join
( select tour_sub_code, count('A') 'countval'
from attendance_master ascs (nolock)
group by tour_sub_code) as newNoOfdays
on newNoOfdays.tour_sub_code = tc.tour_sub_code
where tc.login_id = 'vinod.kumbala'
AND tc.expense = 'Daily Allowance'
AND tc.delete_flag = 'F'
AND tc.status != 'reject'
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