Joining column into MySQL query as a delimited list - mysql

I have a table in MySQL that looks like so:
date | name | status
03-13-2014,Bob Jones,Pending
03-13-2014,George Manuel,Pending
03-13-2014,Tom Grables,Pending
03-13-2014,Frankie Avalon,Approved
03-13-2014,Robert Garcia,Approved
03-14-2014,John Doe,Pending
03-14-2014,John Die,Approved
03-14-2014,John Zoe,Approved
What I am trying to do is grab date, name and status for all rows that say approved. However, I am also wanting to join this query in such a way that each row I grab also has a semicolon delimited list containing the names of those whose status is pending and falls on the same day as an approved. Thus, the output of my query would look something like this:
03-13-2014,Frankie Avalon,Approved,Bob Jones;George Manuel;Tom Grables
03-13-2014,Robert Garcia,Approved,Bob Jones;George Manuel;Tom Grables
Notice that I grabbed the approved requests for 03-13-2014 and added the requests whose status is pending and whose date matches the approved request as a column. I've been messing around with the join statement, and done my Google homework, but have yet to find a way to do this.
Any ideas would be greatly appreciated.

Look into group_concat()
SELECT
GROUP_CONCAT('name` SEPARATOR ',') as NameList
FROM
`tablename`
GROUP BY
`date`

I think this is the logic you want:
select `date`,
group_concat( (case when status = 'Approved' then name end) separator ';') as Approveds,
group_concat( (case when status = 'Pending' then name end) separator ';') as Pendings
from t
group by `date`;
If you really do want pending only on dates where there are no approved, then you need an additional filter:
select `date`,
group_concat( (case when status = 'Approved' then name end) separator ';') as Approveds,
group_concat( (case when status = 'Pending' then name end) separator ';') as Pendings
from t
group by `date`
having `date` in (select `date` from t where status = 'Approved')

Related

Calculating consecutive occurences in MySQL

I have a quick question in relation to windowing in MySQL
SELECT
Client,
User,
Date,
Flag,
lag(Date) over (partition by Client,User order by Date asc) as last_date,
lag(Flag) over (partition by Client,User order by Date asc) as last_flag,
case when Flag = 1 and last_flag = 1 then 1 else 0 end as consecutive
FROM db.tbl
This query returns something like the below. I am trying to work out the number of consecutive times that the Flag column was 1 for each user most recently, if they had 11110000111 then we should take the final three occurences of 1 to determine that they had a consecutive flag of 3 times.
I need to extract the start and end date for the consecutive flag.
How would I go about doing this, can anyone help me :)
If we use the example of 11110000111 then we should extract only 111 and therefore the 3 most recent dates for that customer. So in the below, we would need to take 10.01.2023 as the first date and 24.01.2023 as the last date. The consecutive count should be 3
Output:
Use aggregation and string functions:
WITH cte AS (
SELECT Client, User,
GROUP_CONCAT(CASE WHEN Flag THEN Date END ORDER BY Date) AS dates,
CHAR_LENGTH(SUBSTRING_INDEX(GROUP_CONCAT(Flag ORDER BY Date SEPARATOR ''), '0', '-1')) AS consecutive
FROM tablename
GROUP BY Client, User
)
SELECT Client, User,
NULLIF(SUBSTRING_INDEX(SUBSTRING_INDEX(dates, ',', -consecutive), ',', 1), '') AS first_date,
CASE WHEN consecutive > 0 THEN SUBSTRING_INDEX(dates, ',', -1) END AS last_date,
consecutive
FROM cte;
Another solution with window functions and conditional aggregation:
WITH
cte1 AS (SELECT *, SUM(NOT Flag) OVER (PARTITION BY Client, User ORDER BY Date) AS grp FROM tablename),
cte2 AS (SELECT *, MAX(grp) OVER (PARTITION BY Client, User) AS max_grp FROM cte1)
SELECT Client, User,
MIN(CASE WHEN Flag THEN Date END) AS first_date,
MAX(CASE WHEN Flag THEN Date END) AS last_date,
SUM(Flag) AS consecutive
FROM cte2
WHERE grp = max_grp
GROUP BY Client, User;
See the demo.
Made an attempt to get the result with more simpler queries and here is my approach taking advantage of lastDate and lastFlag column too.
Run here
WITH eTT
AS
( SELECT Client, User, NULLIF(MAX(Date),
(SELECT MAX(Date) FROM tt t2 WHERE t1.Client=t2.Client AND t1.User=t2.User)) as endDate
FROM tt t1 WHERE LastFlag=0 OR LastFlag IS NULL GROUP BY Client, User
)
SELECT Client, User,
(CASE WHEN MAX(endDate) IS NULL THEN NULL ELSE MIN(Date) END) as first_date,
(CASE WHEN MAX(endDate) IS NULL THEN NULL ELSE MAX(Date) END) as last_date,
(CASE WHEN MAX(endDate) IS NULL THEN NULL ELSE COUNT(endDate) END) as consecutive
FROM tt LEFT JOIN eTT USING (Client, User)
WHERE Date >= endDate OR endDate IS null GROUP BY Client, User;
EDIT
The original table doesn't have LastDate and LastFlag columns and were created using OP's initial query.
Since the method used is not apparantly supported but I get an impression that OP somehow manages to do that on their side.
Hence another cte called tt can be added before eTT containing that query.

How to write the a new select query with backward compatibility after adding a new column to a MySQL database

I have a MySQL table running for 4 months and I have a select statement in that table, like below.
SELECT
CONCAT(
YEAR(FROM_UNIXTIME(creation_time)),
'-',
IF(
MONTH(FROM_UNIXTIME(creation_time)) < 10,
CONCAT('0', MONTH(FROM_UNIXTIME(creation_time))),
MONTH(FROM_UNIXTIME(creation_time))
)
) AS Period,
(
COUNT(CASE
WHEN system_name = 'System' THEN 1
ELSE NULL
END)
) AS "Some data",
FROM table_name
GROUP BY
Period
ORDER BY
Period DESC
Lately, I've added a new feature and a column, let's say is_rerun. This value is just added and not exist previously. Now, i would like to write a query with the current statement which checks the system_name and also the is_rerun field and if this field exists and value is 1 then return 1 and if the column not exist or it its value is zero, then return null.
I tried IF EXISTS re_run THEN 1 ELSE NULL, but no luck. I can also insert values for the previous runs but i don't want to do that. Is there any solution. Thanks.
SELECT
CONCAT(
YEAR(FROM_UNIXTIME(creation_time)),
'-',
IF(
MONTH(FROM_UNIXTIME(creation_time)) < 10,
CONCAT('0', MONTH(FROM_UNIXTIME(creation_time))),
MONTH(FROM_UNIXTIME(creation_time))
)
) AS Period,
(
COUNT(CASE
WHEN system_name = 'System' AND IF EXISTS is_rerun THEN 1
ELSE NULL
END)
) AS "Some data",
FROM table_name
GROUP BY
Period
ORDER BY
Period DESC
As a starter: you have a group by query, so you need to put is_rerun in an aggregate function.
Based on your description, I think that something like case(case when is_rerun = 1 then 1 end) should do the work: it returns 1 if any is_rerun in the group is 1, else null.
Or if you can live with 0 instead of null, then you can use a simpler expression: max(is_rerun = 1).
Note that your query could be largely simplified as for the date formating logic and the conditional count. I would phrase it as:
select
date_format(from_unixtime(creation_time),'%Y-%m') period,
sum(system_name = 'System') some_data,
max(is_rerun = 1) is_rerun
from mytable
group by period
order by period desc

Need help DB Query for this scenario

I am unable to derive a SQL query for the following table content.
When i tried below query i am getting above said output. Can someone help me to give the required query for it.
select Name, count(Status) from mytable where Status='Open' group by mytable union
select Name, count(Status) from mytable where Status='Cleared' group by mytable
Use case expressions in the select list to do conditional aggregation.
select Name,
count(case when Status = 'Open' then 1 end) as opencnt,
count(case when Status = 'Cleared' then 1 end) as clearedcnt
from mytable
where Status in ('Open', 'Cleared')
group by Name
COUNT() counts non-null values. The case expressions above returns null when the conditions aren't fulfilled.

How to concatenate column values aggregated out of a group by?

I have this MySQL query that works almost perfectly:
select ConfirmationNumber, ReservationDate, ifnull(CASE TableNumber WHEN 0 THEN 'UNASSIGNED' ELSE TableNumber END,'UNASSIGNED') AS 'Table', CONCAT(LastName, ', ', FirstName) AS 'Customer', Email, Phone, PublicNotes, sum(SleighSeats) + sum(CabSeats) AS Seats
from Reservations
where ReservationDate = '2018-1-25'
and ConfirmationNumber IS NOT NULL
and CancelDate IS NULL
group by TableNumber, Customer
order by TableNumber
It produces this result:
Focus on customer Corbosie... above.
Because there is grouping going on, there are PublicNotes data that I'm missing, because some records are being compressed out of the query. I simply want to concatenate the PublicNotes from all records included in the query, including those being aggregated out.
For example, when I query this way:
select ConfirmationNumber, ReservationDate, ifnull(CASE TableNumber WHEN 0 THEN 'UNASSIGNED' ELSE TableNumber END,'UNASSIGNED') AS 'Table', CONCAT(LastName, ', ', FirstName) AS 'Customer', Email, Phone, PublicNotes, SleighSeats + CabSeats AS Seats
from Reservations
where ConfirmationNumber in ('092550', '764352', '661800')
...it shows you 3 records that got compressed into 1 record (due to grouping) in the first query:
The 2 PublicNotes circled in red are missing because they got aggregated out. How can I maintain the grouping of my first query, while concatenating in the missing PublicNotes with their grouped record?
I think you want group_concat():
select ConfirmationNumber, ReservationDate,
(CASE TableNumber WHEN 0 THEN 'UNASSIGNED' ELSE TableNumber END) AS "Table",
CONCAT(LastName, ', ', FirstName) AS Customer,
Email, Phone,
GROUP_CONCAT(PublicNotes, '|'),
(SUM(SleighSeats) + SUM(CabSeats)) AS Seats
from Reservations
where ReservationDate = '2018-1-25' and
ConfirmationNumber IS NOT NULL and
CancelDate IS NULL
group by ConfirmationNumber, ReservationDate, TableNumber, Customer, email, phone
order by TableNumber;
Notes:
I don't think TableNumber can be NULL, based on the logic, so I removed the IFNULL(). If it can be, then add it back in (or use COALESCE().
I added the additional unaggregated columns to the GROUP BY. This is a good habit for you to use.
The separator for the different notes is a vertical bar. You can choose whatever you like.

Select column(s) corresponding to max/min of another column without joins

I have a table (id, employee_id, device_id, logged_time) [simplified] that logs attendances of employees from biometric devices.
I generate reports showing the first in and last out time of each employee by date.
Currently, I am able to fetch the first in and last out time of each employee by date, but I also need to fetch the first in and last out device_ids of each employee. The entries are not in sequential order of the logged time.
I do not want to (and probably cannot) use joins as in one of the reports the columns are dynamically generated and can lead to thousands of joins. Furthermore, these are subqueries and are joined to other queries to get further details.
A sample setup of the table and queries are at http://sqlfiddle.com/#!9/3bc755/4
The first one just shows lists the entry and exit time by date of every employee
select
attendance_logs.employee_id,
DATE(attendance_logs.logged_time) as date,
TIME(MIN(attendance_logs.logged_time)) as entry_time,
TIME(MAX(attendance_logs.logged_time)) as exit_time
from attendance_logs
group by date, attendance_logs.employee_id
The second one builds up an attendance chart given a date range
select
`attendance_logs`.`employee_id`,
DATE(MIN(case when DATE(`attendance_logs`.`logged_time`) = '2017-09-18' THEN `attendance_logs`.`logged_time` END)) as date_2017_09_18,
MIN(case when DATE(`attendance_logs`.`logged_time`) = '2017-09-18' THEN `attendance_logs`.`logged_time` END) as entry_2017_09_18,
MAX(case when DATE(`attendance_logs`.`logged_time`) = '2017-09-18' THEN `attendance_logs`.`logged_time` END) as exit_2017_09_18,
DATE(MIN(case when DATE(`attendance_logs`.`logged_time`) = '2017-09-19' THEN `attendance_logs`.`logged_time` END)) as date_2017_09_19,
MIN(case when DATE(`attendance_logs`.`logged_time`) = '2017-09-19' THEN `attendance_logs`.`logged_time` END) as entry_2017_09_19,
MAX(case when DATE(`attendance_logs`.`logged_time`) = '2017-09-19' THEN `attendance_logs`.`logged_time` END) as exit_2017_09_19
/*
* dynamically generated columns for dates in date range
*/
from `attendance_logs`
where `attendance_logs`.`logged_time` >= '2017-09-18 00:00:00' and `attendance_logs`.`logged_time` <= '2017-09-19 23:59:59'
group by `attendance_logs`.`employee_id`;
Tried:
Similar to max and min logged_time of each date using case, tried to select the device_id where logged_time is max/min.
```MIN(case
when
`attendance_logs.logged_time` = MIN(
case when DATE(`attendance_logs`.`logged_time`)
= '2017-09-18' THEN `attendance_logs`.`logged_time` END
)
then `attendance_logs`.`device_id` end) as entry_device_2017_09_18 ```
This results in invalid use of group by
A quick hack for your query to pick the device id for in and out by using GROUP_CONCAT with in SUBSTRING_INDEX
SUBSTRING_INDEX(GROUP_CONCAT(case when DATE(`l`.`logged_time`) = '2017-09-18' THEN `l`.`device_id` END ORDER BY `l`.`device_id` desc),',',1) exit_device_2017_09_18,
Or if device id will be same for each in and its out then simply it can be written with GROUP_CONCAT only
GROUP_CONCAT(DISTINCT case when DATE(`l`.`logged_time`) = '2017-09-18' THEN `l`.`device_id` END)
DEMO
To avoid joins I suggest you try "correlated subqueries" instead:
select
employee_id
, logdate
, TIME(entry_time) entry_time
, (select MIN(l.device_id)
from attendance_logs l
where l.employee_id = d.employee_id
and l.logged_time = d.entry_time) entry_device
, TIME(exit_time) exit_time
, (select MAX(l.device_id)
from attendance_logs l
where l.employee_id = d.employee_id
and l.logged_time = d.exit_time) exit_device
from (
select
attendance_logs.employee_id
, DATE(attendance_logs.logged_time) as logdate
, MIN(attendance_logs.logged_time) as entry_time
, MAX(attendance_logs.logged_time) as exit_time
from attendance_logs
group by
attendance_logs.employee_id
, DATE(attendance_logs.logged_time)
) d
;
see: http://sqlfiddle.com/#!9/06e0e2/3
Note: I have used MIN() and MAX() on those subqueries only to avoid any possibility that these return more than one value. You could use limit 1 instead if you prefer.
Note also: I do not normally recommend correlated subqueries as they can cause performance issues, but they do supply the data you need.
oh, and please try to avoid using date as a column name, it isn't good practice.