SQL - Display Count of records even if 0 - sql

I am trying to create an SQL query in MS Access that will show how many appointments an employee will have in the current month, even if it is 0. It is very similar to this question, but i can't get it to work with a WHERE clause.
I have 3 tables:
tblEmployees
-employeeID PK
-FirstName ETC
tblEngineersAppts1
-ApptID PK
-EmployeeID*
tblEngineersAppts2
-DiaryID PK
-ApptDate
-ApptID*
I want to show all employees, a COUNT of all appointments (DiaryID) in tblEngineersAppts2 even if there are none where ApptDate is the current month.
This is my query, it only shows employees that have an appointment in the current month, it doesn't show those who have none.
SELECT tblEmployees.EmployeeID, Count(tblEngineersAppts2.DiaryID) AS CountOfDiaryID
FROM (tblEmployees
LEFT JOIN tblEngineersAppts1 ON tblEmployees.EmployeeID = tblEngineersAppts1.EmployeeID)
LEFT JOIN tblEngineersAppts2 ON tblEngineersAppts1.ApptID = tblEngineersAppts2.ApptID
WHERE (((Format$([ApptDate],'MM/YY'))='03/17'))
GROUP BY tblEmployees.EmployeeID;
Thanks

The problem is when you put the WHERE condition you make the LEFT JOIN an INNER JOIN
WHERE (((Format$([ApptDate],'MM/YY'))='03/17'))
So Include the ApptDate constraint in the ON condition.
SELECT tblEmployees.EmployeeID, Count(tblEngineersAppts2.DiaryID) AS CountOfDiaryID
FROM (tblEmployees
LEFT JOIN tblEngineersAppts1 ON tblEmployees.EmployeeID = tblEngineersAppts1.EmployeeID)
LEFT JOIN tblEngineersAppts2
ON ( tblEngineersAppts1.ApptID = tblEngineersAppts2.ApptID
AND Format$([ApptDate],'MM/YY')='03/17'
)
GROUP BY tblEmployees.EmployeeID;

I think you could do something like this:
SELECT
tblEmployees.EmployeeID,
(
SELECT Count(tblEngineersAppts2.DiaryID)
FROM tblEngineersAppts1
JOIN tblEngineersAppts2 ON tblEngineersAppts1.ApptID = tblEngineersAppts2.ApptID
WHERE tblEmployees.EmployeeID = tblEngineersAppts1.EmployeeID
AND (((Format$([ApptDate],'MM/YY'))='03/17'))
) AS CountOfDiaryID
FROM
tblEmployees

Related

SQL tables joined with max

I'm working with two tables. I have a full list of groups in table A, and a list of each group member that has been reviewed in table B. So table B is a log of all review records for those members for each group.
select a.Group_Name, Max(b.Request_Review_Date)
From GroupTable a
Left Outer Join GroupReviews b ON a.Group_Name = b.Group_Name
Group By a.Group_Name
What I am trying to return is the full list of groups from table A, and find the latest review date from table B for each of those groups.
I have researched and tried all or most of the inner & outer joins, apply methods....but its just not giving me the results. Can anyone point me in the right direction? Or am I having to bring back two result sets and compare in my ASP code-behind?
Try a CTE then join back to it
WITH Recent AS
(
select group_name, max(Request_Review_Date) AS 'MaxReviewDate'
from GroupReviews
group by group_name
)
select a.group_name, MaxReviewDate
from GroupTable a left join Recent
on group_name = a.group_name
if you need the value for max for all the a.group name rows the ypu should join the subquery for max date
select a.Group_Name, t.max_date
left join (
select b.Group_Name, Max(b.Request_Review_Date) max_date
from GroupReviews b
Group By b.Group_Name
) t on t.Group_Name = a.Group_Name

how can I get the selected columns fully and the sum column separately

SELECT f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date,sum(payments.paid_amount)
FROM payments
LEFT JOIN family ON family.id = payments.family_id
LEFT JOIN teachers ON family.teacher_id = teachers.t_id
How can I get the selected columns fully and the sum column separately?
because that sum function makes all the selected result one row
SELECT f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date
FROM payments
LEFT JOIN family ON family.id = payments.family_id
LEFT JOIN teachers ON family.teacher_id = teachers.t_id
This query is working fine without the sum column
You didn't tell the database, which column to use for aggregating the data. Don't know which database you are using, but some complain, that there is no GROUP BY statement in the SQL text.
Please try with the following query:
SELECT f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date,sum(payments.paid_amount)
FROM payments
LEFT JOIN family ON family.id = payments.family_id
LEFT JOIN teachers ON family.teacher_id = teachers.t_id
GROUP BY f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date
GROUP BY tells the database, which are the key columns in the aggregation.
If you want all the payments, use a subquery or join:
SELECT f_name, l_name, t.first_name, t.t_id, p.p_id, p.paid_amount, p.family_id, date,
(select sum(p.paid_amount) from payments) as all_paid
FROM payments p LEFT JOIN
family f
ON f.id = p.family_id LEFT JOIN
teachers t
ON f.teacher_id = tetchers.t_id;
SELECT f_name,l_name,t.first_name,t.t_id,p_id,paid_amount,family_id,date,sum(p.paid_amount)
FROM payments p,family f,teachers t where f.id = p.family_id and f.teacher_id = t.t_id
Group by f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id
You can add date column also in Group by expression based on your requirement. Example:
f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date

SQL server SELECT with join performance issue

Sorry about the saga here but am trying to explain everything.
We have 2 databases that I would like to join some tables in.
1 database holds sales data from various different stores/sites. This database is quite large (over 3mill rows currently) This table is ItemSales
The other holds application data from an in house web app. These tables are Departments and GroupItems
I would like to create a query that joins 2 tables from the app database with the sales database table. This is so we can group some items together for a date range and see the amount sold for example.
My first attempt was (DealId being the variable that it is grouped on in the App):
SELECT d.Id, d.ItemNo, d.UnitValue, d.NoGST, d.ItemStartDate, d.ItemEndDate,
(SELECT SUM(ItemQty) AS Expr1
FROM Sales.dbo.ItemSales AS s
WHERE (Store = d.SiteId) AND (ItemNo = d.ItemNo) AND (ItemSaleDate >= d.ItemStartDate) AND (ItemSaleDate <= d.ItemEndDate)) AS ItemsSold, Sales.dbo.ItemSales.ItemDesc, Departments.Description
FROM Departments INNER JOIN
Sales.dbo.ItemSales ON Departments.Id = Sales.dbo.ItemSales.ItemDept RIGHT OUTER JOIN
GroupItems AS d ON Sales.dbo.ItemSales.ItemNo = d.ItemNo
WHERE (d.DealId = 11)
GROUP BY d.Id, d.ItemNo, d.UnitValue, d.NoGST, d.ItemStartDate, d.ItemEndDate, ItemDesc, Departments.Description, d.SiteId
ORDER BY d.Id
This does exactly what I want which is:
-Give me all the details from the GroupItems table (UnitValue, ItemStartDate, ItemEndDate etc)
-Gives me the SUM() on the ItemQty column for the amount sold (plus the description etc)
-Returns NULL for something with no sales for the period
It is VERY slow though. To the point that if the GroupItems table has more than about 7 items in it, it times out.
Second attempt has been:
SELECT d.Id, d.ItemNo, d.UnitValue, d.NoGST, d.ItemStartDate, d.ItemEndDate, SUM(ItemQty) AS ItemsSold, Sales.dbo.ItemSales.ItemDesc, Departments.Description
FROM Departments INNER JOIN
Sales.dbo.ItemSales ON Departments.Id = Sales.dbo.ItemSales.ItemDept RIGHT OUTER JOIN
GroupItems AS d ON Sales.dbo.ItemSales.ItemNo = d.ItemNo
WHERE (Store = d.SiteId) AND (d.DealId = 11) AND (Sales.dbo.ItemSales.ItemSaleDate >= d.ItemStartDate) AND (Sales.dbo.ItemSales.ItemSaleDate <= d.ItemEndDate)
GROUP BY d.Id, d.ItemNo, d.UnitValue, d.NoGST, d.ItemStartDate, d.ItemEndDate, ItemDesc, Departments.Description
ORDER BY d.Id
This is very quick and does not time out but does not return the NULLs for no sales items in the ItemSales table. This is a problem as we need to see nothing or 0 for a no sales item otherwise people will think we forgot to check that item.
Can someone help me come up with a query please that returns everything from the GroupItems table, shows the SUM() of items sold and doesn't time out? I have also tried a SELECT x WHERE EXISTS (Subquery) but this also didn't return the NULLs for me but I may have had that one wrong.
If you want everything from GroupItems regardless of the sales, use it as the base of the query and then use left outer joins from there. Something along these lines:
SELECT GroupItems.Id, GroupItems.ItemNo, GroupItems.UnitValue, GroupItems.NoGST,
GroupItems.ItemStartDate, GroupItems.ItemEndDate,
Sales.ItemDesc,
SUM(ItemQty) AS SumOfSales,
Departments.Description
FROM GroupItems
LEFT OUTER JOIN #tempSales AS Sales ON
Sales.ItemNo = GroupItems.ItemNo
AND Sales.Store = GroupItems.SiteId
AND Sales.ItemSaleDate >= GroupItems.ItemStartDate
AND Sales.ItemSaleDate <= GroupItems.ItemEndDate
LEFT OUTER JOIN Departments ON Departments.Id = Sales.ItemDept
WHERE GroupItems.DealId = 11
GROUP BY GroupItems.Id, GroupItems.ItemNo, GroupItems.UnitValue, GroupItems.NoGST,
GroupItems.ItemStartDate, GroupItems.ItemEndDate,
Sales.ItemDesc,
SUM(ItemQty) AS SumOfSales,
Departments.Description
ORDER BY GroupItems.Id
Does changing the INNER JOIN to Sales.dbo.ItemSales into a LEFT OUTER JOIN to Sales.dbo.ItemSales and changing the RIGHT OUTER JOIN to GroupItems into an INNER JOIN to GroupItems fix your issue?

How to include "zero" / "0" results in COUNT aggregate?

I've just got myself a little bit stuck with some SQL. I don't think I can phrase the question brilliantly - so let me show you.
I have two tables, one called person, one called appointment. I'm trying to return the number of appointments a person has (including if they have zero). Appointment contains the person_id and there is a person_id per appointment. So COUNT(person_id) is a sensible approach.
The query:
SELECT person_id, COUNT(person_id) AS "number_of_appointments"
FROM appointment
GROUP BY person_id;
Will return correctly, the number of appointments a person_id has. However, a person who has 0 appointments isn't returned (obviously as they are not in that table).
Tweaking the statement to take person_id from the person table gives me something like:
SELECT person.person_id, COUNT(appointment.person_id) AS "number_of_appointments"
FROM appointment
JOIN person ON person.person_id = appointment.person_id
GROUP BY person.person_id;
This however, will still only return a person_id who has an appointment and not what I want which is a return with persons who have 0 appointments!
Any suggestions please?
You want an outer join for this (and you need to use person as the "driving" table)
SELECT person.person_id, COUNT(appointment.person_id) AS "number_of_appointments"
FROM person
LEFT JOIN appointment ON person.person_id = appointment.person_id
GROUP BY person.person_id;
The reason why this is working, is that the outer (left) join will return NULL for those persons that do not have an appointment. The aggregate function count() will not count NULL values and thus you'll not get a zero.
If you want to learn more about outer joins, here is a nice tutorial: http://sqlzoo.net/wiki/Using_Null
You must use LEFT JOIN instead of INNER JOIN
SELECT person.person_id, COUNT(appointment.person_id) AS "number_of_appointments"
FROM person
LEFT JOIN appointment ON person.person_id = appointment.person_id
GROUP BY person.person_id;
if you do the outer join (with the count), and then use this result as a sub-table, you can get 0 as expected (thanks to the nvl function)
Ex:
select P.person_id, nvl(A.nb_apptmts, 0) from
(SELECT person.person_id
FROM person) P
LEFT JOIN
(select person_id, count(*) as nb_apptmts
from appointment
group by person_id) A
ON P.person_id = A.person_id
USE join to get 0 count in the result using GROUP BY.
simply 'join' does Inner join in MS SQL so , Go for left or right join.
If the table which contains the primary key is mentioned first in the QUERY then use LEFT join else RIGHT join.
EG:
select WARDNO,count(WARDCODE) from MAIPADH
right join MSWARDH on MSWARDH.WARDNO= MAIPADH.WARDCODE
group by WARDNO
.
select WARDNO,count(WARDCODE) from MSWARDH
left join MAIPADH on MSWARDH.WARDNO= MAIPADH.WARDCODE group by WARDNO
Take group by from the table which has Primary key and count from the another table which has actual entries/details.
To change even less on your original query, you can turn your join into a RIGHT join
SELECT person.person_id, COUNT(appointment.person_id) AS "number_of_appointments"
FROM appointment
RIGHT JOIN person ON person.person_id = appointment.person_id
GROUP BY person.person_id;
This just builds on the selected answer, but as the outer join is in the RIGHT direction, only one word needs to be added and less changes. - Just remember that it's there and can sometimes make queries more readable and require less rebuilding.
The problem with a LEFT JOIN is that if there are no appointments, it will still return one row with a null, which when aggregated by COUNT will become 1, and it will appear that the person has one appointment when actually they have none. I think this will give the correct results:
SELECT person.person_id,
(SELECT COUNT(*) FROM appointment WHERE person.person_id = appointment.person_id) AS 'Appointments'
FROM person;

i want to modify this SQL statement to return only distinct rows of a column

select
picks.`fbid`,
picks.`time`,
categories.`name` as cname,
options.`name` as oname,
users.`name`
from
picks
left join categories
on (categories.`id` = picks.`cid`)
left join options
on (options.`id` = picks.oid)
left join users
on (users.fbid = picks.`fbid`)
order by
time desc
that query returns a result that like:
my question is.... I would like to modify the query to select only DISTINCT fbid's. (perhaps the first row only sorted by time)
can someone help with this?
select
p2.fbid,
p2.time,
c.`name` as cname,
o.`name` as oname,
u.`name`
from
( select p1.fbid,
min( p1.time ) FirstTimePerID
from picks p1
group by p1.fbid ) as FirstPerID
JOIN Picks p2
on FirstPerID.fbid = p2.fbid
AND FirstPerID.FirstTimePerID = p2.time
LEFT JOIN Categories c
on p2.cid = c.id
LEFT JOIN Options o
on p2.oid = o.id
LEFT JOIN Users u
on p2.fbid = u.fbid
order by
time desc
I don't know why you originally had LEFT JOINs, as it appears that all picks must be associated with a valid category, option and user... I would then remove the left, and change them to INNER joins instead.
The first inner query grabs for each fbid, the FIRST entry time which will result in a single entity for the FBID. From that, it re-joins to the picks table for the same ID and timeslot... then continues for the rest of the category, options, users join criteria of that single entry.
2 options, you could write a group by clause.
Or you could write a nested query joined back to itself to get pertinent info.
Nested aliased table:
SELECT
n.fBids
FROM
MyTable t
INNER JOIN
(SELECT DISTINCT fBids
FROM MyTable) n
ON n.ID = t.ID
Or group by option
SELECT fBId from MyTable
GROUP BY fBID
select picks.`fbid`, picks.`time`, categories.`name` as cname,
options.`name` as oname, users.`name` from picks left join categories
on (categories.`id` = picks.`cid`) left join options on (options.`id` = picks.oid)
left join users on (users.fbid = picks.`fbid`)
order by time desc GROUP BY picks.`fbid`
select
picks.fbid,
MIN(picks.time) as first_time,
MAX(picks.time) as last_time
from
picks
group by
picks.fbid
order by
MIN(picks.time) desc
However, if you want only distinct fbid's you cannot display cname and other columns at the same time.