Hopefully very simple SQL question - I'm just blacking out :)
I have a table of vendors (id, name, description, url). It used to be the web service returned them all sorted by id. After a while, I was asked to return sorted by name. Now they want me to allow them to change the order manually - to showcase new vendors.
Suppose I create another table, VendorOrder with (vendorid, placement), what can I put in the Order By section of the original query, to return the vendors sorted by placement?
As always, thanks in advance.
Guy
select
vendor.id,
vendor.name,
vendor.description,
vendor.url
from
vendors,
vendorOrder
where
vendors.id = vendorOrder.vendorId
order by
vendorOrder.placement;
Make sure that you find exactly one vendorId in vendorOrder for each id in vendor, otherwise use a left join between the tables.
Related
I need to brind a lot of columns from several tables using LEFT JOIN. My starting point is the orders table and I bring the vendor name from the "Address_table". Then I add another table with order details and then the shipping information of each order detail.
My problem is that I need to bring a different record from "Address_table" to refer onether id's detailed in shipment table as of "origin_id" and "destination_id".
In other words, "address_id", "origin_id" and "destination_id" are all records from "Address_table". I brought the first one related to the vendor, how can I retrieve the other two?
Example
Thanks in advance
Your question is not exactly clear in terms of the tables and their relationships. It is, however, clear what the problem is. You need to join against the same table twice using different columns.
In order to do that you need to use table aliases. For example, you can do:
select *
from shipment s
left join address_table a on a.address_id = s.origin_id
left join address_table b on b.address_id = s.destination_id
In this example the table address_table is joined twice against the table shipment; the first time we use a as an alias, the second time b. This way you can differentiate how to pick the right columns and make the joins work as you need them to.
I currently have three tables.
master_tradesmen
trades
master_tradesmen_trades (joins the previous two together in a many-to-many relationship). The 'trade_id' and 'master_tradesman_id' are the foreign keys.
Here is what I need to happen. A user performs a search and types in a trade. I need a query that displays all of the information from the master_tradesmen table whose trade in the master_tradesmen_trade table matches the search. For example, if 'plumbing' is typed in the search bar (trade_id 1), all of the columns for Steve Albertsen (master_tradesman_id 6) and Brian Terry (master_tradesman_id 8) would be displayed from the master_tradesmen table. As a beginner to SQL, trying to grasp the logic of this is about to make my head explode. I'm hoping that someone with more advanced SQL knowledge can wrap their head around this much easier than I can. Note: the 'trades' column in master_tradesmen is for display purposes only, not for querying. Thank you so much in advance!
You have a catalog for the tradesmen, & another catalog for the trades.
The trades should only appear once in the trades catalog in order to make your DB more consistent
Then you have your many-to-many table which connects the trades & master tradesmen tables.
If we want to get the tradesmen according to the given trade in the input, we should first
know the id of that trade which has to be unique, so in your DB you would have something
like the img. below :
Now we can make a query to select the id of trade :
DECLARE #id_trade int = SELECT trade_id FROM trades WHERE trade_name LIKE '%plumbing%'
Once we know the trading id, we can redirect to the 'master_tradesmen_trades' table to know the name of the people how work that trade :
SELECT * FROM master_tradesmen_trades WHERE trade_id = #id_trade
You will get the following result :
You may say, 'But there is still something wrong with it, as i am still not able to see the tradesmen', this is the moment when we make an inner join:
SELECT * FROM master_tradesmen_trades trades_and_tradesmen
INNER JOIN master_tradesman tradesmen
ON tradesmen.id = trades_and_tradesmen.master_tradesmen_id
WHERE trade_id = #id_trade
IF you need to see specific columns, you can do :
SELECT first_name, last_name, city, state FROM master_tradesmen_trades trades_and_tradesmen
INNER JOIN master_tradesman tradesmen
ON tradesmen.id = trades_and_tradesmen.master_tradesmen_id
WHERE trade_id = #id_trade
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.
I need to find the sum of the prices of a number of products, however the prices are stored in a different table to products that need pricing.
But, there is a catch, it needs to select these items based on criteria from a third table too.
So, I need the sum of the price of all products in Table 1 where CutID in Table 2 = 001.
Table 1 and Table 2 are linked on SCID, one to many respectively.
If this makes no sense tell me and I will try to clarify?
Thanks,
Bob P
Based on your question, I don't think there's a need for VBA. Excel formulas should be sufficient.
Add a few columns to your primary table. In these columns, use vlookup() to get all your information in one place, including the criteria.
If you only need to sum based on one criteria, use sumif(). If there's multiple criteria, use sumproduct().
Generally, with Access, I initially try to work with something as close a possible to a standard SQL query for ease of maintenance and portability. This ran for me in Access 2010:
SELECT Products.ProductID, Sum(Prices.Price) AS PriceSum
FROM Prices INNER JOIN (Critera INNER JOIN Products ON Critera.SCID = Products.SCID) ON Prices.ProductID = Products.ProductID
WHERE Critera.CutID="001"
GROUP BY Products.ProductID;
Please let us know if that works with your data (I'm not sure of your column names, either).
Say I've employee table where any employee can be related to any other employee (many to many). Each employee has many characteristics that are stored separately.
emp: id,name
related: name,emp1role,emp1id,emp2role,emp2id
chars: empid,name,value
I want to get all the characteristics of employees who are related via 'xxx' along with the relation. I am currently using this query:
SELECT c.empid, c.Name, c.Value
FROM chars as c, related as r
WHERE r.name='xxx' AND (r.emp1id=c.empid OR r.emp2id=c.empid)
This works and it gives related employees one after another i.e. if emp22 & emp43 are related via 'xxx' then I am getting chars of emp43 followed by emp22 and so on. This way I am able to know which two employees are related (which is needed). However, I want to know if this order is mere luck or is it well-defined. This is in SQLite.
If it is not defined way, how else can I do it? Also, I need to know their respective roles. I want to preferably do it in one query. Can you think of some other query?
Thanks in advance,
Manish
PS: These are not actual tables. They are here for simplicity of asking question.
In SQL, ordering of the result is undefined unless you have an explicit ORDER BY clause in your query. So I believe you want:
SELECT c.empid, c.Name, c.Value
FROM chars as c, related as r
WHERE r.name='xxx' AND (r.emp1id=c.empid OR r.emp2id=c.empid)
ORDER BY c.empid ASC
I tend to add a unique field (such as a primary key) at the end, to if not get an obvious ordering when there are multiple records matching in all other order fields, at least get deterministic ordering. But that's largely a matter of style and choice; it's by no means required.