This sounds like a very simple query but I have never needed this calculation before. I'm using SQL Management Studio and SQL Server 2008.
I have a table ct_workers which contains individual employees and a second table cs_facilities which shows the sites that they work at.
The table ct_workers has a field person which is the primary ID for each employee and has a field facility which links the employees to cs_facilities via a field guid
I'm looking to display all workers that have 2 or more facilities.
I've though about using Excel or rownumber but surely that must be a simple efficient way of doing this?
Can anyone assist please?
Thanks,
You can use a GROUP BY with HAVING
SELECT cw.person
FROM ct_workers cw
GROUP BY cw.person
HAVING COUNT(DISTINCT cw.facility) >= 2
Your question suggests that you can use aggregation:
select w.person
from ct_workers w
group by w.person
having min(w.facility) <> max(w.facility); -- at least 2 values
However, if the person is the unique key in ct_workers, then a person can only be in one facility. So, your question would not make sense. You should actually have a junction table with one row per person and per facility.
Related
(This is a general SQL question, but I am specifically using MSAccess 2010 so looking for how to do this with Access' flavor of SQL)
I have a table called offices which has id, office_name, num_desks.
Another table called employees which has id, employee_name.
And a final table called employee_offices which has id, office_id, employee_id.
I can assign employees to offices via employee_offices.
I am trying to generate a report which shows all offices and the employees assigned to the, but also includes blank lines for any empty desks in that office.
I realize a "simple" way to do this would be to create a desks table with id, office_id, delete the num_desks column from the offices table and change employee_offices to something like employee_desks. Then my report would be a simple LEFT OUTER JOIN and it would include all the unassigned desks. However for the sake of sanity (in this case, there is no contextual difference between desks), I am not going to do this. Plus if I start deleting desks I have referential constraints to deal with (which obviously exist for a good reason and would catch the fact that I am leaving employees without a desk), but I just want to be able to change the number of desks.
I can calculate the number of empty desks (or lack of desks) through the following command:
SELECT
office_id,
num_desks - num_employees AS desk_diff,
MAX(0, num_desks - num_employees) AS blank_rows_to_add
FROM offices LEFT OUTER JOIN (
SELECT office_id, COUNT(employee_id) AS num_employees
FROM employee_offices
GROUP BY office_Id
) AS num_employees_by_office ON offices.id = num_employees_by_office.office_id
Is there a way to take this number (blank_rows_to_add) and somehow utilze it to add that many blank rows (or at least the row only has the office_id/office_name) to a report showing a list of employees by office? I know this can be done with VBA but I am specifically looking for an SQL method that also doesn't include a temp table if at all possible.
Thank you.
I have two tables in a Database
and
I need to retrieve the number of staff per manager in the following format
I've been trying to adapt an answer to another question
SELECT bankNo AS "Bank Number",
COUNT (*) AS "Total Branches"
FROM BankBranch
GROUP BY bankNo
As
SELECT COUNT (*) AS StaffCount ,
Employee.Name AS Name
FROM Employee, Stafflink
GROUP BY Name
As I look at the Group BY I'm thinking I should be grouping by The ManID in the Stafflink Table.
My output with this query looks like this
So it is counting correctly but as you can see it's far off the output I need to get.
Any advice would be appreciated.
You need to join the Employee and Stafflink tables. It appears that your FROM clause should look like this:
FROM Employee INNER JOIN StaffLink ON Employee.ID = StaffLink.ManID
You have to join the Eployee table twice to get the summary of employees under manager
select count(*) as StaffCount,Manager.Name
from Employee join Stafflink on employee.Id = StaffLink.EmpId
join Employee as Manager on StaffLink.ManId = Manager.Id
Group by Manager.Name
The answers that advise you on how to join are correct, assuming that you want to learn how to use SQL in MS Access. But there is a way to accomplish the same thing using the ACCESS GUI for designing queries, and this involves a shorter learning curve than learning SQL.
The key to using the GUI when more than one table is involved is to realize that you have to define the relationships between tables in the relationship manager. Once you do that, designing the query you are after is a piece of cake, just point and click.
The tricky thing in your case is that there are two relationships between the two tables. One relationship links EmpId to ID and the other links ManId to ID.
If, however, you want to learn SQL, then this shortcut will be a digression.
If you don't specify a join between the tables, a so called Cartesian product will be built, i.e., each record from one table will be paired with every record from the other table. If you have 7 records in one table and 10 in the other you will get 70 pairs (i.e. rows) before grouping. This explains why you are getting a count of 7 per manager name.
Besides joining the tables, I would suggest you to group on the manager id instead of the manager name. The manager id is known to be unique per manager, but not the name. This then requires you to either group on the name in addition, because the name is in the select list or to apply an aggregate function on the name. Each additional grouping slows down the query; therefore I prefer the aggregate function.
SELECT
COUNT(*) AS StaffCount,
FIRST(Manager.Name) AS ManagerName
FROM
Stafflink
INNER JOIN Employee AS Manager
ON StaffLink.ManId = Manager.Id
GROUP BY
StaffLink.ManId
I don't know if it makes a performance difference, but I prefer to group on StaffLink.ManId than on Employee.Id, since StaffLink is the main table here and Employee is just used as lookup table in this query.
Today while writing one of the many queries that every developer in my company write every day I stumbled upon a question.
The DBMS we are using is Sql Server 2008
Say for example I write a query like this in the usual PERSON - DEPARTMENT db example
select * from person where id = '01'
And this query returns one row:
id name fk_department
01 Joe dp_01
The question is: is there a way (maybe using an addon) to make sql server write and execute a select like this
select * from department where id = 'dp_01'
only by for example clicking with the mouse on the cell containing the fk value (dp_01 in the example query)? Or by right click and selecting something like ("Go to pointed value")?
I hope I didn't wrote something stupid or impossible by definition
Not really, but that seems like a silly thing to do. Why would you want to confuse an id with a department name?
Instead, you could arrange things so you could do:
select p.*
from person p
where department = 'dp_01';
You would do this by adding a computed column department that references a scalar function that looks up the value in the department table. You can read about computed columns here.
However, a computed column would have bad performance characteristics. In particular, it would basically require a full table scan on the person table, even if that is not appropriate.
Another solution is to create a view, v_person that has the additional columns you want. Then you would do:
select p.*
from v_person p
where department = 'dp_01';
Why can't you write yourself by saying
select * from department where id =
(select fk_department from person where id = '01')
So I'm taking a course on learning basic SQL (using Oracle), and I felt like I had become fairly fluent with using SELECT statements (grouping, joining, having, etc), but now I'm at a loss on how to deal with this latest problem.
I need to write a statement that would only display rows with more than one piece of data. So, say I had
COMPANY PRODUCT
One Car
One Book
Two Game
it should only list company 'One'. But I can't find anything online to help me.
Select Company
From YourTableName
Group By Company
Having Count(*) > 1
better way to know count of each company is :
Select Company,Count(*)
From Table
Group By Company
Having Count(*) > 1
I have 2 tables with a many-to-any relationship. For the example we will call the tables "Guys" and Girls" There is a junction table that contains the related primary keys...who has dated who.
If I want to find all the girls that Guy 1 has dated, I do a select on the junction table selecting all girls with guys.ID. This give me a RecordSet. Now to find the names of the girls, I need to select from the girls table a row using the key from each RecordSet row.
Isn't there an easier way? Since I've defined the relationships in Access I would think that there must be a way to build a single query. How do I do that?
SELECT girls.name
FROM (guys
INNER JOIN junct ON guys.guyID = junct.guyID)
INNER JOIN girls ON junct.girlID = girls.girlID
WHERE guys.guyID = [whatever id you're looking for]