I am trying to join several fields in one table to a field in another table. They will be differentiated by the values in another field. I am unsure how this join should work and would appreciate advice. Here's examples of the tables
Bldg|EMeter|GMeter|HMeter|CMeter
Bld1_1______1______1______1_____
Bld2_2______3______328____2_____
Bld2_NULL___4______NULL___NULL
Utility|Meter|TotCost|
E_______5_____20______
C_______5_____80______
H_______5_____123______
G_______5_____654______
E_______6_____999______
E_______7_____205______
G_______6_____200______
G_______7_____40______
These tables obviously just representative of what I'm dealing with. But I'm trying to write a query to match all the meter columns from the first table to the meter column in the second table, but only if the utility value matches the first letter in the meter (EMeter goes with E, GMeter goes with G, etc.) Also the building's can have one more than one record, because they can have more than one meter of a type. I'm trying to get a cost for each building, for each type of meter, so I add all the separate meters together for each building (ie. How bldg2 has two meters for G, those will each have total costs that need to be added together. I'm trying to run a group by buildings in my query to total all those together). I'm trying to use a select query to join the meters in the first one with the meters in the second one where the utilities match, but I can't really get the syntax or design of how to do that at all. Eventually I want to have a select by query displaying something like this
Bldg|ECost|GCost|HCost|CCost
Bld1_2000__39483_20____3829_
Bld2_2034__385___2839__3010_
Since the names of columns in the first table are fixed, you can build a query that uses an outer join, and then group by with SUM(), like this:
SELECT
m.Bldg
, SUM(e.TotCost) AS ECost
, SUM(g.TotCost) AS GCost
, SUM(h.TotCost) AS HCost
, SUM(c.TotCost) AS CCost
FROM tblBldgMeters m
LEFT OUTER JOIN qryMtrHistory e ON e.Utility='E' AND m.EMeter=e.Meter
LEFT OUTER JOIN qryMtrHistory g ON g.Utility='G' AND m.GMeter=g.Meter
LEFT OUTER JOIN qryMtrHistory h ON h.Utility='H' AND m.HMeter=h.Meter
LEFT OUTER JOIN qryMtrHistory c ON c.Utility='C' AND m.CMeter=c.Meter
GROUP BY m.Bldg
It is saying JOIN expression not supported
This is a problem with MS-Access SQL engine. You can rewrite this into a different query:
SELECT
m.Bldg
, SUM(e.TotCost * SWITCH(e.Utility='E', 1, true, 0)) AS ECost
, SUM(g.TotCost * SWITCH(g.Utility='G', 1, true, 0)) AS GCost
, SUM(h.TotCost * SWITCH(h.Utility='H', 1, true, 0)) AS HCost
, SUM(c.TotCost * SWITCH(c.Utility='C', 1, true, 0)) AS CCost
FROM tblBldgMeters m
LEFT OUTER JOIN qryMtrHistory e ON AND m.EMeter=e.Meter
LEFT OUTER JOIN qryMtrHistory g ON AND m.GMeter=g.Meter
LEFT OUTER JOIN qryMtrHistory h ON AND m.HMeter=h.Meter
LEFT OUTER JOIN qryMtrHistory c ON AND m.CMeter=c.Meter
GROUP BY m.Bldg
This moves the condition from the JOIN into a SWITCH.
Related
I am working on a query that has fields called ios_app_id, android_app_id and app_id.
The app_id from downloads table can be either ios_app_id or android_app_id in the products table.
Is it correct that because of that I cannot just run a simple join of downloads and products table on on p.ios_app_id = d.app_id and then join again on on p.android_app_id = d.app_id? Would that cause an incorrect number of records?
select p.product_id, d.date, d.downloads,
from products p
inner join download d
on p.ios_app_id = d.app_id
UNION
select p.product_id, d.date, d.downloads
from products p
inner join download d
on p.android_app_id = d.app_id
I would try:
select p.product_id, d.date, d.downloads,
from products p
inner join downloads d
on p.ios_app_id = d.app_id
inner join downloads d
on p.android_app_id = d.app_id
Basically I am trying to understand why the union here is needed instead of just joining the two fields twice? Thank you
Just join twice:
select p.product_id,
coalesce(di.date, da.date),
coalesce(di.downloads, da.downloads)
from products p left join
downloads di
on p.ios_app_id = di.app_id left join
downloads da
on p.android_app_id = da.app_id;
This should be more efficient than your method with union. Basically, it attempts joining using the two ids. The coalesce() combines the results into a single column.
Remember that the purpose of an INNER JOIN is to get the values that exists on BOTH sets of data (lets called them table A and table B), using a specific column to join them. In your example, if you try to do the INNER JOIN twice, what would happen is that the first time you execute the INNER JOIN, the complete PRODUCTS table is your table A, and you obtain all the products that have downloaded the ios_app, but now (and this is the key part) this result becomes your new dataset, so it becomes your new table A for the next inner join. And thats the issue, cause what you would want is to join the whole table again, not just the result of the first join, but thats not how it works. This is why you need to use the UNION, cause you need to obtain your results independently and then add them.
An alternative would be to use LEFT JOIN, but you could get null values and duplicates -and its not too "clean"-. So, for your particular case, I think using UNION is much clearer and easier to understand.
If you do left join in first query it will work.
create table all_products as (select p.product_id, d.date, d.downloads,
from products p
left join downloads d
on p.ios_app_id = d.app_id)
select a.product_id, d.date, d.downloads from all_products a left join downloads d
on a.android_app_id = d.app_id inner join
I am attempting to access data from the following tables:
OrgPlanYear
ProjOrgPlnYrJunction
DC
DCMaxEEContribLevel
DCNonDiscretionaryContribLevel
Basically, I need to inner join OrgPlanYear + DC and ProjOrgPlnYrJunction then I need to Left Join the remaining tables (tables 4 and 5) due to the fact the tables 1-3 have all the rows I need and only some have data in tables 4-5. I need several variables from each table. I also need the WHERE function to be across all fields (meaning I want all this data for a select group where projectID=919).
Please help!
I have tried many things with errors including attempting to use the Design Query side (i.e. JOIN function issues, badly formatted FROM function, etc.)! Here is an example of one excluding all variables I need:
SELECT
ProjOrgPlnYrJunction.fkeyProjectID, OrgPlanYear.OrgName, DC.PlanCode, DCNonDiscretionaryContribLevel.Age,DCNonDiscretionaryContribLevel.Service
FROM
(((OrgPlanYear INNER JOIN DC ON OrgPlanYear.OrgPlanYearID = DC.fkeyOrgPlanYearID) INNER JOIN ProjOrgPlnYrJunction ON OrgPlanYear.OrgPlanYearID = ProjOrgPlnYrJunction.fkeyOrgPlanYearID)
LEFT JOIN
(SELECT DCNonDiscretionaryContribLevel.Age AS Age, DCNonDiscretionaryContribLevel.Service AS Service FROM DCNonDiscretionaryContribLevel WHERE ProjOrgPlnYrJunction.fkeyProjectID)=919)
LEFT JOIN (
SELECT DCMaxEEContribLevel.EEContribRoth FROM EEContribRoth WHERE ProjOrgPlnYrJunction.fkeyProjectID)=919)
ORDER BY OrgPlanYear.OrgName;
Main issues with your query:
Missing ON clauses for each LEFT JOIN.
Referencing other table columns in SELECT and WHERE of a different subquery (e.g., FROM DCNonDiscretionaryContribLevel WHERE ProjOrgPlnYrJunction.fkeyProjectID).
Unmatched parentheses around subqueries and joins per Access SQL requirements.
See below adjusted SQL that now uses short table aliases. Be sure to adjust SELECT and ON clauses with appropriate columns.
SELECT p.fkeyProjectID, o.OrgName, DC.PlanCode, dcn.Age, dcn.Service, e.EEContribRoth
FROM (((OrgPlanYear o
INNER JOIN DC
ON o.OrgPlanYearID = DC.fkeyOrgPlanYearID)
INNER JOIN ProjOrgPlnYrJunction p
ON o.OrgPlanYearID = p.fkeyOrgPlanYearID)
LEFT JOIN
(SELECT Age AS Age, Service AS Service
FROM DCNonDiscretionaryContribLevel
WHERE fkeyProjectID = 919) AS dcn
ON dcn.fkeyProjectID = p.fkeyOrgPlanYearID)
LEFT JOIN
(SELECT EEContribRoth
FROM EEContribRoth
WHERE fkeyProjectID = 919) AS e
ON e.fkeyProjectID = p.fkeyProjectID
ORDER BY o.OrgName;
I have to make a list of customer who do not have any invoice but have paid an invoice … maybe twice.
But with my code (stated below) it contains everything from the left join. However I only need the lines highlighted with green.
How should I make a table with only the 2 highlights?
Select paymentsfrombank.invoicenumber,paymentsfrombank.customer,paymentsfrombank.value
FROM paymentsfrombank
LEFT OUTER JOIN debtors
ON debtors.value = paymentsfrombank.value
You only want to select columns from paymentsfrombank. So why do you even join?
select invoice_number, customer, value from paymentsfrombank
except
select invoice_number, customer, value from debtors;
(This requires exact matches as in your example, i.e. same amount for the invoice/customer).
There are two issues in your SQL. First, you need to join on Invoice number, not on value, as joining on value is pointless. Second, you need to only pick those payments where there are no corresponding debts, i.e. when you left-join, the table on the right has "null" in the joining column. The SQL would be something like this:
SELECT paymentsfrombank.invoicenumber,paymentsfrombank.customer,paymentsfrombank.value
FROM paymentsfrombank
LEFT OUTER JOIN debtors
ON debtors.InvoiceNumber = paymentsfrombank.InvoiceNumber
WHERE debtors.InvoiceNumber is NULL
in mysql we usually have this way to flip the relation and extract the rows that dosen't have relation.
Select paymentsfrombank.invoicenumber,paymentsfrombank.customer,paymentsfrombank.value
FROM paymentsfrombank
LEFT OUTER JOIN debtors
ON debtors.value = paymentsfrombank.value where debtors.value is null
You can use NOT EXISTS :
SELECT p.*
FROM paymentsfrombank p
WHERE NOT EXISTS (SELECT 1 FROM debtors d WHERE d.invoice_number = p.invoice_number);
However, the LEFT OUTER JOIN would also work if you add filtered with WHERE Clause to filtered out only missing customers that haven't any invoice information :
SELECT p.invoicenumber, p.customer, p.value
FROM paymentsfrombank P LEFT OUTER JOIN
debtors d
ON d.InvoiceNumber = p.InvoiceNumber
WHERE d.InvoiceNumber IS NULL;
Note : I have used table alias (p & d) that makes query to easier read & write.
I have the following tables with the following attributes:
Op(OpNo, OpName, Date)
OpConvert(OpNo, M_OpNo, Source_ID, Date)
Source(Source_ID, Source_Name, Date)
Fleet(OpNo, S_No, Date)
I have the current multiple JOIN query which gives me the results that I want:
SELECT O.OpNo AS Op_NO, O.OpName, O.Date AS Date_Entered, C.*
FROM Op O
LEFT OUTER JOIN OpConvert C
ON O.OpNo = C.OpNo
LEFT OUTER JOIN Source D
ON C.Source_ID = D.Source_ID
WHERE C.OpNo IS NOT NULL
The problem is this. I need to join the Fleet table on the previous multiple JOIN statement to attach the relevant S_No to the multiple JOIN table. Would I still be able to accomplish this using a LEFT OUTER JOIN or would I have to use a different JOIN statement? Also, which table would I JOIN on?
Please note that I am only familiar with LEFT OUTER JOINS.
Thanks.
I guess in your case you could use INNER JOIN or LEFT JOIN (which is the same thing as LEFT OUTER JOIN in SQL Server.
INNER JOIN means that it will only return records from other tables only if there are corresponding records (based on the join condition) in the Fleet table.
LEFT JOIN means that it will return records from other tables even if there are no corresponding records (based on the join condition) in the Fleet table. All columns from Fleet will return NULL in this case.
As for which table to join, you should really join the table that makes more logical sense based on your data structure.
Yes, you can use all tables mentioned before in your join conditions. Actually, JOINS (no matter of INNER, LEFT OUTER, RIGHT OUTER, CROSS, FULL OUTER or whatever) are left- associative, i. e. they are implicitly evaluated as if they would have been included in parentheses from the left as follows:
FROM ( ( ( Op O
LEFT OUTER JOIN OpConvert C
ON O.OpNo = C.OpNo
)
LEFT OUTER JOIN Source D
ON C.Source_ID = D.Source_ID
)
LEFT OUTER JOIN Fleet
ON ...
)
This is similar to how + or - would implicitly use parentheses, i. e.
2 + 3 - 4 - 5
is evaluated as
(((2 + 3) - 4) - 5)
By the way: If you use C.OpNo IS NOT NULL, then the LEFT OUTER JOIN Source D is treated as if it were an INNER JOIN, as you are explicitly removing all the "OUTER" rows.
The original query returns 160k rows. When I add the LEFT OUTER JOIN:
LEFT OUTER JOIN Table_Z Z WITH (NOLOCK) ON A.Id = Z.Id
the query returns only 150 rows. I'm not sure what I'm doing wrong.
All I need to do is add a column to the query, which will bring back a code from a different table. The code could be a number or a NULL. I still have to display NULL, hence the reason for the LEFT join. They should join on the "id" columns.
SELECT <lots of stuff> + the new column that I need (called "code").
FROM
dbo.Table_A A WITH (NOLOCK)
INNER JOIN
dbo.Table_B B WITH (NOLOCK) ON A.Id = B.Id AND A.version = B.version
--this is where I added the LEFT OUTER JOIN. with it, the query returns 150 rows, without it, 160k rows.
LEFT OUTER JOIN
Table_Z Z WITH (NOLOCK) ON A.Id = Z.Id
LEFT OUTER JOIN
Table_E E WITH (NOLOCK) ON A.agent = E.agent
LEFT OUTER JOIN
Table_D D WITH (NOLOCK) ON E.location = D.location
AND E.type = 'Organization'
AND D.af_type = 'agent_location'
INNER JOIN
(SELECT X , MAX(Version) AS MaxVersion
FROM LocalTable WITH (NOLOCK)
GROUP BY agemt) P ON E.agent = P.location AND E.Version = P.MaxVersion
Does anyone have any idea what could be causing the issue?
When you perform a LEFT OUTER JOIN between tables A and E, you are maintaining your original set of data from A. That is to say, there is no data, or lack of data, in table E that can reduce the number of rows in your query.
However, when you then perform an INNER JOIN between E and P at the bottom, you are indeed opening yourself up to the possibility of reducing the number of rows returned. This will treat your subsequent LEFT OUTER JOINs like INNER JOINs.
Now, without your exact schema and a set of data to test against, this may or may not be the exact issue you are experiencing. Still, as a general rule, always put your INNER JOINs before your OUTER JOINs. It can make writing queries like this much, much easier. Your most restrictive joins come first, and then you won't have to worry about breaking any of your outer joins later on.
As a quick fix, try changing your last join to P to a LEFT OUTER JOIN, just to see if the Z join works.
You have to be very careful once you start with LEFT JOINs.
Let's suppose this model: You have tables Products, Orders and Customers. Not all products necessarily have been ordered, but every order must have customer entered.
Task: Show all products, and if the product was ordered, list the ordering customers; i.e., product without orders will be shown as one row, product with 10 orders will have 10 rows in the resultset. This calls for a query designed around FROM Products LEFT JOIN Orders.
Now someone could think "OK, Customer is always entered into orders, so I can make inner join from orders to customers". Wrong. Since the table Customers is joined through left-joined table Orders, it has to be left-joined itself... otherwise the inner join will propagate into the previous level(s) and as a result, you will lose all products that have no orders.
That is, once you join any table using LEFT JOIN, any subsequent tables that are joined through this table, need to keep LEFT JOINs. But it does not mean that once you use LEFT JOIN, all joins have to be of that type... only those that are dependent on the first performed LEFT JOIN. It would be perfectly fine to INNER JOIN the table Products with another table Category for example, if you only want to see Products which have a category set.
(Answer is based on this answer: http://www.sqlservercentral.com/Forums/Topic247971-8-1.aspx -> last entry)