Imagine I have four tables:
Agents
| agent_id | agent_name |
Teams
| team_id | team_name |agent_id |
Menu
| menu_id | menu_name |
Team_assignment
| menu_id | team_id|
I need to write a query that selects all agents that are assigned to all teams and all queues and disregard the ones that are not assigned to a queue. Note that every agent is always assigned to a team but it's not necessary that the agent is assigned to a queue.
Since you stated that this is for a school project, I'll try to stay within the guidelines mentioned here: How do I ask and answer homework questions?
From what I can make up from your question you basically want to select all the data from the different tables joining them on one of the columns in the first table a equals = a column from the second table b. Most commonly where the primary key from one table equals the foreign key from another table. Then you want to add conditions to your query where for example some column from table 1 equals = some value.
Do you catch my drift? 😏
No?
You want to SELECT a.*, b.* everything FROM table Agents a JOINing table Teams b ON column a.agent_id being equal to = column b.agent_id
You probably want to JOIN another table, lets say Team_assignment c ON column c.team_id being equal to = b.team_id.
You can JOIN more tables in the same way.
Sadly, I do not understand what you mean by the ones that are not assigned to a queue but it sounds like a condition that your query needs to match, so WHERE the potential column a.is_assigned_to_queue equals = true AND for example a.agent_name IS NOT NULL
If you got this far you should have been able to catch onto my drift 😎, congrats. This way hopefully you also got a better understanding of how building query works, instead of me just blatantly giving you the answer and you learn nothing from it. Like this:
SELECT a.*, b.*, c.*, d.* FROM Agents a
JOIN Teams b ON a.agent_id = b.agent_id
JOIN Team_assignment c ON c.team_id = b.team_id
JOIN Menu d ON d.menu_id = c.menu_id
WHERE a.is_assigned_to_queue = true
AND a.agent_name IS NOT NULL;
Now it is possible copy and pasting the snippet above will not work, that is because I'm not an SQL expert and I had to refresh my old memories about SQL myself by googling it. But that's the nice part of actually learning it. Being able to explain it to someone else :)
Related
How to remove duplicate values a = b and b = a?
with a as(select w.id , w.doc, w.org
, d.name_s, d.name_f, d.name_p, d.spec
, o.name, o.extid
from crm_s_workplaces w
join crm_s_docs d on d.id=w.doc
join crm_s_orgs o on o.id=w.org
where d.active=1 and d.cst='NY' and w.active=1 and w.cst='NY' and o.active=1
and
o.cst='NY')
select a1.doc, a2.doc,
a1.org,a1.name_s,a1.name_f,a1.name_p,a2.name_s,a2.name_f,a2.name_p from a a1
join a a2 on
a1.name_s=a2.name_s and
substr(a1.name_f,1,1)=substr(a2.name_f,1,1) and
substr(a1.name_p,1,1)=substr(a2.name_p,1,1) and
a1.org=a2.org and
a1.spec<>a2.spec
order by a1.name_s `enter code here`
ER model diagram:
Repeat example:
Sometimes comes across a1.spec > a2.spec:
What you are calling "duplicates" are actually not duplicates in your database.
You basically have multiple doc records for what could be the same person or not. See that even their names do not always match. For instace,
doc_id 1131385 has NAME_F = "Gabr" while
doc_id 1447530 has NAME_F = "Gabor"
In your database these are two different entities, and you cannot match them using primary key. You can try to join on the first, middle and last names, but as you can see in the above example with Gabor/Gabr, even that would not work.
Can you change the schema of the db? If so you need to separate the docs in one table - 1 record per doctor. And have the specialization in a separate table with the folloing columns:
spec_id (int, PK)
doc_id (foreign key to Doc table)
specialization
that way, if you have 1 doctor with 3 specs, he/she will show up only once in doc table, and multiple times in spec table.
I just notice something else. You have spec field in table workplaces. why? If you meant to say that Doc Gabor works as admin in hospital 1 but as a Therapist in hospital 2, you can do that. However, you have to remove the spec field from the doc table and only use the spec in workplaces table.
I have two tables called resource and resource_owners.
The resource_owners table contains two columns called resource_id and owner_id.
resource_id | owner_id |
-------------+-----------
The resource table contains two relevant columns: parentresource_id and id.
parentresource_id | id |
-------------------+------
resource_owners.resource_id, resource.id and resource.parentresource_id are all join columns between the two tables. Now what I want to do is the following:
For every row in the resource table, take the value in id, match it with a corresponding resource_owners.resource_id, retrieve the corresponding resource_owners.owner_id value (call it $owner_value), then set resource_owners.owner_id to $owner_value where resource_owners.resource_id equals resource.parentresource_id.
In conversational terms, this is what I want to do: For each resource, I want to re-assign the parent-resource's owner_id to be the resource's owner_id.
I've tried to wrap my head around this problem and it looks like I'll need two different table joins (resource.id with resource_owners.resource_id and resource.parentresource_id with resource_owners.resource_id).
Can someone point me in the right direction? Is what I want even possible with a single query? I'm okay with a PostgreSQL script as well if that works better for my use case.
I'm not sure what database you are using but you should be able to accomplish using the logic below if I understood your question correctly:
UPDATE RESOURCE_OWNER SET
OWNER_ID = UP.OWNER_ID
FROM (SELECT rc.ID, TMP.OWNER_ID FROM (SELECT RSC.ID, ROWRS.OWNER_ID, ROWRS.RESOURCE_ID FROM RESOURCE RSC JOIN RESOURCE_OWNER ROWRS
ON RSC.ID = ROWRS.RESOURCE_ID) TMP JOIN RESOURCE rc on rc.PARENTRESOURCE_ID = TMP.RESOURCE_ID) UP WHERE RESOURCE_OWNER.RESOURCE_ID = UP.ID;
I have a database in MS Access, and I ran into a problem with empty values. I have 3 tables that are connected to eachother. Lets say Table1 contains people, Table 2 contains Phone numbers, and Table 3 connects table 1 and 2, having both their ID's so I could later see what person has what numbers by using the IDs.
What I want from access is that it would display a person even if he/she doesn't have a number assigned, and also a number when there are no people assigned to it.
Something like this:
Persons_name |Phone_number
--------------------------
Fred | 123
| 222
Anna |
The tables look something like this:
People People_phones Phones
------------- -------------- ------------
ID ID ID
Persons_name People_ID Phone_number
Phones_ID
So far I've managed to get access to show either table 1's null values or table 2's null values, but not both.
As E Mett indicated above, your looking for a full outer join which doesn't handle directly. Here is an example of what he's suggesting:
How do I write a full outer join query in access
JB
In sql jargon what you are looking for is an outer join.
This is unfortunately not available in Ms Access because it is rarely needed.
You should create two queries, one using a left join and the other with a right join.
Then use the UNION keyword to combine the results
I am having a slow brain day...
The tables I am joining:
Policy_Office:
PolicyNumber OfficeCode
1 A
2 B
3 C
4 D
5 A
Office_Info:
OfficeCode AgentCode OfficeName
A 123 Acme
A 456 Acme
A 789 Acme
B 111 Ace
B 222 Ace
B 333 Ace
... ... ....
I want to perform a search to return all policies that are affiliated with an office name. For example, if I search for "Acme", I should get two policies: 1 & 5.
My current query looks like this:
SELECT
*
FROM
Policy_Office P
INNER JOIN Office_Info O ON P.OfficeCode = O.OfficeCode
WHERE
O.OfficeName = 'Acme'
But this query returns multiple rows, which I know is because there are multiple matches from the second table.
How do I write the query to only return two rows?
SELECT DISTINCT a.PolicyNumber
FROM Policy_Office a
INNER JOIN Office_Info b
ON a.OfficeCode = b.OfficeCode
WHERE b.officeName = 'Acme'
SQLFiddle Demo
To further gain more knowledge about joins, kindly visit the link below:
Visual Representation of SQL Joins
Simple join returns the Cartesian multiplication of the two sets and you have 2 A in the first table and 3 A in the second table and you probably get 6 results. If you want only the policy number then you should do a distinct on it.
(using MS-Sqlserver)
I know this thread is 10 years old, but I don't like distinct (in my head it means that the engine gathers all possible data, computes every selected row in each record into a hash and adds it to a tree ordered by that hash; I may be wrong, but it seems inefficient).
Instead, I use CTE and the function row_number(). The solution may very well be a much slower approach, but it's pretty, easy to maintain and I like it:
Given is a person and a telephone table tied together with a foreign key (in the telephone table). This construct means that a person can have more numbers, but I only want the first, so that each person only appears one time in the result set (I ought to be able concatenate multiple telephone numbers into one string (pivot, I think), but that's another issue).
; -- don't forget this one!
with telephonenumbers
as
(
select [id]
, [person_id]
, [number]
, row_number() over (partition by [person_id] order by [activestart] desc) as rowno
from [dbo].[telephone]
where ([activeuntil] is null or [activeuntil] > getdate()
)
select p.[id]
,p.[name]
,t.[number]
from [dbo].[person] p
left join telephonenumbers t on t.person_id = p.id
and t.rowno = 1
This does the trick (in fact the last line does), and the syntax is readable and easy to expand. The example is simple but when creating large scripts that joins tables left and right (literally), it is difficult to avoid that the result contains unwanted duplets - and difficult to identify which tables creates them. CTE works great for me.
Consider two tables. Technician table has fields like T_ID,T_Name. Project table has fields like P_ID,P_Name, P_Date.
Now, since a Technician can work on many projects and a project can be done by many Technicians. Therefore, as evident, there is a many to many relationship between the two tables. Break the many to many, and create a new table called Assignment which consists of the foreign keys T_ID and P_ID.
Here is the question: I want to find out a list of who a particular technician (Technician with T_ID = 1 worked with over the last month (April/2011). For example if Technician 1 worked with Tech 2 and 3 then they qualify for the above query result and i would like tech 2 and Tech 3 T_ID T_name.
The answer can be also based on two queries linked.
Kindly let me know what will be the query for the mentioned problem.
This would find all the people who worked on assignments with the technician who has ID = 10. Maybe:
SELECT t.T_ID, t.T_Name
FROM Technician t, Project p, Assignments a
WHERE t.T_ID = a.T_ID and p.P_ID = a.P_ID
and a.P_ID IN (SELECT assign.P_ID FROM Assignments assign, Projects proj WHERE assign.T_ID = 10 and assign.P_ID = proj.P_ID and (proj.P_Date - getdate() <= 30))
The date is a little bit of a guess as I'm not sure on the syntax, however the rest should get the information you want.
Give Assignment table a primary key of its own (because composite keys suck).
The two ? characters represent the ID of the Technician that you're asking
who worked with. For example: "Who worked with Technician 5", the ? would be
5's.
SELECT
a1.T_ID
FROM
Assignment a1
WHERE
a1.A_ID IN (
SELECT assignment.A_ID
FROM Assignment a2
WHERE a2.T_ID = ?
)
AND a1.T_ID != ?
;