I have a table, event_sessions that contains a session_submitted_by ID and a session_submitter_type. I need to JOIN session_submitted_by to one of two different tables, based on the contents of session_submitter_type.
I can't just do an LEFT OUTER JOIN on both tables and choose whichever returns content because both tables may contain an ID match.
Here is my improper SQL/pseudo-code that shows what I'm trying to accomplish:
SELECT es.event_session_id,
subu.first_name + ' ' + subu.last_name as submitted_by_name,
subu.email as submitter_email
FROM event_session es
CASE WHEN es.session_submitter_type = 'speaker'
THEN
LEFT OUTER JOIN speakers subu
ON subu.speaker_id = es.session_submitted_by
ELSE
LEFT OUTER JOIN users subu
ON subu.user_id = es.session_submitted_by
END
Any suggestions how to code this without having to resort to a UNION?
Interesting question. I would do it like so:
SELECT es.event_session_id,
coalesce(spk.first_name, usr.first_name)
+ ' ' + coalesce(spk.last_name, usr.last_name) as submitted_by_name,
coalesce(spk.email, usr.email) as submitter_email
FROM event_session es
LEFT OUTER JOIN speakers spk
ON es.session_submitter_type = 'speaker' and spk.speaker_id = es.session_submitted_by
LEFT OUTER JOIN users usr
ON es.session_submitter_type <> 'speaker' and usr.user_id = es.session_submitted_by
You basically use two left outer joins, and one only one of them is ever going to be active for any given row of event_session.
Note: If session_submitter_type is nullable then you need to add a NULL check in the second join to maintain the semantics of your pseudo code.
Related
I'm trying to perform the query below on SQL Server:
SELECT
[dbo].[Machine].[MachineID],
[dbo].[Machine].[CompanyID],
[dbo].[Company].[AccountRef],
[dbo].[Machine].[ProductTypeID],
[dbo].[Machine].[SerialNo],
[dbo].[Machine].[InstallationDate],
[dbo].[Machine].[SalesTypeID],
[dbo].[SalesType].[SalesType],
[dbo].[Machine].[LeasingCompanyID],
[dbo].[LeasingCompany].[Name],
[dbo].[Machine].[QuarterlyRentalCost],
[dbo].[Machine].[Term],
[dbo].[Machine].[ExpiryDate],
[dbo].[Machine].[Scales],
[dbo].[Machine].[Chips],
[dbo].[Machine].[ContractTypeID],
[dbo].[ContractType].[ContractType],
[dbo].[Machine].[ContractCost],
[dbo].[Machine].[InvoiceDate],
[dbo].[Machine].[ServiceDueDate],
[dbo].[Machine].[ServiceNotes],
[dbo].[Machine].[modelID],
[dbo].[Machine].[Model],
[dbo].[Machine].[IMP_Machine Reference],
[dbo].[Machine].[Smart]
FROM
[dbo].[Machine], [dbo].[Company], [dbo].[SalesType], [dbo].[LeasingCompany], [dbo].[ContractType]
LEFT JOIN
[dbo].[Machine] as A ON A.[CompanyID] = [dbo].[Company].[CompanyID]
LEFT JOIN
[dbo].[Machine] as B ON B.[SalesTypeID] = [dbo].[SalesType].[SalesTypeID]
LEFT JOIN
[dbo].[Machine] as C ON C.[LeasingCompanyID] = [dbo].[LeasingCompany].[LeasingCompanyID]
LEFT JOIN
[dbo].[Machine] as D ON D.[ContractTypeID] = [dbo].[ContractType].[ContractTypeID] ;
But for some reason that i cannot see for the life of me, the destination column name in the bottom 3 join statements is reporting "The multi part identifier could not be bound".
Could anyone assist please?
Many Thanks,
You were pretty close, for readability, you dont need the extensive [dbo].[table] all over. You can define it once in the from clause with an alias, then use that alias the rest of the way through. Also, make the alias make sense to the context of the table as you will see in this below. LeasingCompany lc, SalesType st, etc.
Also, I try to have indented so I always know the first table of the join relationship and the JOIN indented on where it is being joined to. Then I keep the orientation of the from/to table aliases the same context.
Since the machine table is used once and joined to 4 different lookup tables, you can reuse the same "m" alias to each underlying. Think of a tree and branches. The root tree is your "Machine", and all the branches are the lookups.
SELECT
m.MachineID,
m.CompanyID,
c.AccountRef,
m.ProductTypeID,
m.SerialNo,
m.InstallationDate,
m.SalesTypeID,
st.SalesType,
m.LeasingCompanyID,
lc.LeasingCompany.Name,
m.QuarterlyRentalCost,
m.Term,
m.ExpiryDate,
m.Scales,
m.Chips,
m.ContractTypeID,
ct.ContractType,
m.ContractCost,
m.InvoiceDate,
m.ServiceDueDate,
m.ServiceNotes,
m.modelID,
m.Model,
m.IMP_Machine Reference,
m.Smart
FROM
Machine m
LEFT JOIN Company c
ON m.CompanyID = c.CompanyID
LEFT JOIN SalesType st
ON m.SalesTypeID = st.SalesTypeID
LEFT JOIN LeasingCompany lc
ON m.LeasingCompanyID = lc.LeasingCompanyID
LEFT JOIN ContractType ct
ON m.ContractTypeID = ct.ContractTypeID ;
I am having a rows with two different IDs in database. Now I am trying to show two different data columns in one row, I tried something like this:
SELECT
[dbo].[fnHexToNumber]([Participant].[Stake]) AS [PlayerStake],
(SELECT [dbo].[fnHexToNumber]([Stake])
FROM [dbo].[Participant_Complete]
WHERE [ParticipantId] = [Fold].[HouseParticipantId]) AS [HouseStake],
([dbo].[fnHexToNumber]([Participant].[Stake]) + [dbo].[fnHexToNumber]([C].[RunningWinLoss])) AS [PlayerStakeAfterRound],
(SELECT [dbo].[fnHexToNumber]([Stake])
FROM [dbo].[Participant_Complete]
WHERE [ParticipantId] = [Fold].[HouseParticipantId]) - [dbo].[fnHexToNumber]([C].[RunningWinLoss]) AS [HouseStakeAfterRound]
FROM
[dbo].[Round_Complete] AS [C]
INNER JOIN
[dbo].[Fold_Complete] AS [Fold] ON [Fold].[Id] = [C].[Id]
INNER JOIN
[dbo].[Participant_Complete] AS [Participant] ON [Participant].[ParticipantId] = [Fold].[PlayerParticipantId]
This works, but as you can see it will do two trips to database for same nested select. How can I make this only one round trip?
You are referring to the subqueries. That is not a "round trip to the database", which usually refers to an application calling a query.
All the square braces make the query hard to read, but you can fix this using apply:
SELECT [dbo].[fnHexToNumber](p.[Stake]) AS PlayerStake,
h.HouseStake,
([dbo].[fnHexToNumber](p.[Stake]) + [dbo].[fnHexToNumber]([C].RunningWinLoss)) AS PlayerStakeAfterRound,
(h.HouseStake - [dbo].fnHexToNumber(C.RunningWinLoss)) AS HouseStakeAfterRound
FROM [dbo].[Round_Complete] c JOIN
[dbo].[Fold_Complete] f
ON f.[Id] = c.[Id] JOIN
[dbo].[Participant_Complete] pc
ON px.[ParticipantId] = f.[PlayerParticipantId] OUTER APPLY
(SELECT [dbo].[fnHexToNumber]([Stake]) as HouseStake
FROM [dbo].[Participant_Complete] pch
WHERE pch.ParticipantId = f.HouseParticipantId
) h
Just join the same table a second time instead of pulling the data as sub-queries.
Also, you only need brackets around names if the names contain a space (which is bad practice in general). If the names don't have a space, the brackets are totally extraneous.
SELECT
dbo.fnHexToNumber(Participant.Stake) AS PlayerStake,
dbo.fnHexToNumber(p.Stake) as HouseStake,
(dbo.fnHexToNumber(Participant.Stake) + dbo.fnHexToNumber(C.RunningWinLoss)) AS PlayerStakeAfterRound,
dbo.fnHexToNumber(p.Stake) - dbo.fnHexToNumber(c.RunningWinLoss) as HouseStakeAfterRound
FROM dbo.Round_Complete AS C
INNER JOIN dbo.Fold_Complete AS Fold
ON Fold.Id = C.Id
INNER JOIN dbo.Participant_Complete AS Participant
ON Participant.ParticipantId = Fold.PlayerParticipantId
INNER JOIN dbo.Participant_Complete AS p
ON p.ParticipantId = Fold.HouseParticipantId
Is it possible to not pull in duplicate rows when creating a table from multiple table joins in Vertica SQL? I am wanting to filter out entire duplicate rows - so rows where all column values in that row are the same as another row.
I tried doing this using Group By after searching online, but I still find a large amount of duplicate rows. FYI I am checking for duplicates by downloading my data, opening with excel, and removing duplicates. My end goal is to not have to download the data because we are using a system where we do not have a method for re-loading the data onto the server system we are using (#ThanksCerner).
I was reading a few methods where you create a temporary table and delete duplicates, but also read that it is not recommended to use DELETE for tables with a large # of records, so I was trying to avoid that.
Thanks in advance!
Update: This is the query I am using. I will work on creating some test data I can share for it
SELECT DISTINCT c.condition_code, c.condition_primary_display,
c.effective_date_id AS condition_effective_date,
bc.member_id, bc.plan_name, bc.payer_name,
e.facility, e.service_delivery_location, e.hospital_service_display,
e.encounter_type_display, e.encounter_type_primary_display,
e.discharge_disposition_display, e.admission_source_display,
e.status_display, e.actual_arrival_dt_tm, e.discharge_dt_tm,
p.full_name AS patient_name, p.postal_cd, p.county_display,
p.state_primary_display,
pd.birth_date, pd.ethnicity_primary_display, pd.gender_primary_display,
pr.race_display,
po.name AS provider_name, po.provider_id,
epr.relationship_type_primary_display
FROM PH_D_Person p
LEFT OUTER JOIN PH_D_Person_Demographics pd
ON p.empi_id = pd.empi_id AND p.population_id = pd.population_id
LEFT OUTER JOIN PH_D_Person_Race pr
ON pd.empi_id = pr.empi_id AND pd.population_id = pr.population_id
LEFT OUTER JOIN PH_F_Condition c
ON pr.empi_id = c.empi_id AND pr.population_id = c.population_id
LEFT OUTER JOIN PH_F_Encounter e
ON c.encounter_id = e.encounter_id AND c.empi_id = e.empi_id AND
c.population_id = e.population_id
LEFT OUTER JOIN PH_F_Encounter_Benefit_Coverage bc
ON e.encounter_id = bc.encounter_id AND e.empi_id = bc.empi_id AND
e.population_id = bc.population_id
LEFT OUTER JOIN PH_F_Encounter_Personnel_Reltn epr
ON bc.encounter_id = epr.encounter_id AND bc.empi_id = epr.empi_id AND
bc.population_id = epr.population_id
LEFT OUTER JOIN PH_D_Provider po
ON epr.provider_id = po.provider_id
WHERE c.condition_code IN ('J44.0', 'J44.1', 'J44.9', 'J47.1', 'J47.0',
'J47.9', 'J43.2', 'J43.9', 'J41.8', 'J41.1', 'J43.8', 'J43.1', 'J41.0',
'J43.0', 'J42')
AND year(e.actual_arrival_dt_tm) ='2017'
AND year(e.discharge_dt_tm) ='2017'
ORDER BY bc.member_id DESC;
I have 2 tables
tableAssembly, with columns SerialNumber, Brick1SerialNumber, Brick2SerialNumber,DateInserted
tableBricks, with columns SerialNumber, Lot, Weight, DateMeasured
In VB.NET(WinForms) I have been able to get the reportviewer control to work and print out information from both tables and also to enable/disable columns, and apply filters such as LIKE
In case it isn't clear tableAssembly.Brick1SerialNumber = tableBricks.SerialNumber
What I now want to do is when a user prints out a report from tableAssembly, I want them to be able to filter based on Brick1SerialNumber.Lot or Brick2SerialNumber.Lot or Brick1SerialNumber.DateMeasured or Brick2SerialNumber.DateMeasured
I understand I need to INNER JOIN tableAssembly.Brick1SerialNumber = tableBricks.SerialNumber AND tableAssembly.Brick2SerialNumber = tableBricks.SerialNumber
Do I also need to INNER JOIN the other columns from tableBricks to columns in tableAssembly? or does the INNER JOIN of Brick1SerialNumber = SerialNumber and Brick2SerialNumber = Serial make it so I can filter based on .Lot?
There are two ways to approach this. 1) join to tableBricks twice (probably not necessary for this condition) or attach it once, using both foreign keys (works for this condition, but not for all conditions).
Try this query:
SELECT tableAssembly.*
FROM tableAssembly INNER JOIN tableBricks
ON tableAssembly.Brick1SerialNumber = tableBricks.SerialNumber
OR tableAssembly.Brick2SerialNumber = tableBricks.SerialNumber
WHERE tableBricks.Lot = 99 --actually means Brick1.Lot or Brick2.Lot
AND tableBricks.DateMeasured = '1/1/2000'
If you need a specific Lot or DateMeasured for Brick1 and Brick2 (not the same values), then try this query:
SELECT tableAssembly.*
FROM tableAssembly INNER JOIN tableBricks AS tableBricks1
ON tableAssembly.Brick1SerialNumber = tableBricks1.SerialNumber
INNER JOIN tableBricks AS tableBricks2
ON tableAssembly.Brick2SerialNumber = tableBricks2.SerialNumber
WHERE tableBricks1.Lot = 98
AND tableBricks2.Lot = 99
AND tableBricks1.DateMeasured = '1/1/2000'
AND tableBricks2.DateMeasured = '1/2/2000'
I'm trying to retrieve a list of components via my computer_system, BUT if a computer system's graphics card is set to null (I.e. It has an onboard), the row isn't returned by my select statement.
I've been trying to use COALESCE without results. I've also tried with and OR in my WHERE clause, which then just returns my computer system with all different kinds of graphic cards.
Relevant code:
SELECT
computer_system.cs_id,
computer_system.cs_name,
motherboard.name,
motherboard.price,
cpu.name,
cpu.price,
gfx.name,
gfx.price
FROM
public.computer_case ,
public.computer_system,
public.cpu,
public.gfx,
public.motherboard,
public.ram
WHERE
computer_system.cs_ram = ram.ram_id AND
computer_system.cs_cpu = cpu.cpu_id AND
computer_system.cs_mb = motherboard.mb_id AND
computer_system.cs_case = computer_case.case_id AND
computer_system.cs_gfx = gfx.gfx_id; <-- ( OR computer_system.cs_gfx IS NULL)
Returns:
1;"Computer1";"Fractal Design"; 721.00; "MSI Z87"; 982.00; "Core i7 I7-4770K "; 2147.00; "Crucial Gamer"; 1253.00; "ASUS GTX780";3328.00
Should I use Joins? Is there no easy way to say return the requested row, even if there's a bloody NULL value. Been struggling with this for at least 2 hours.
Tables will be posted if needed.
EDIT: It should return a second row:
2;"Computer2";"Fractal Design"; 721.00; "MSI Z87"; 982.00; "Core i7 I7-4770K "; 2147.00; "Crucial Gamer"; 1253.00; "null/nothing";null/nothing
You want a LEFT OUTER JOIN.
First, clean up your code so you use ANSI joins so it's readable:
SELECT
computer_system.cs_id,
computer_system.cs_name,
motherboard.name,
motherboard.price,
cpu.name,
cpu.price,
gfx.name,
gfx.price
FROM
public.computer_system
INNER JOIN public.computer_case ON computer_system.cs_case = computer_case.case_id
INNER JOIN public.cpu ON computer_system.cs_cpu = cpu.cpu_id
INNER JOIN public.gfx ON computer_system.cs_gfx = gfx.gfx_id
INNER JOIN public.motherboard ON computer_system.cs_mb = motherboard.mb_id
INNER JOIN public.ram ON computer_system.cs_ram = ram.ram_id;
Then change the INNER JOIN on public.gfx to a LEFT OUTER JOIN:
LEFT OUTER JOIN public.gfx ON computer_system.cs_gfx = gfx.gfx_id
See PostgreSQL tutorial - joins.
I very strongly recommend reading an introductory tutorial to SQL - at least the PostgreSQL tutorial, preferably some more material as well.
It looks like it's just a bracket placement issue. Pull the null check and the graphics card id comparison into a clause by itself.
...
computer_system.cs_case = computer_case.case_id AND
(computer_system.cs_gfx IS NULL OR computer_system.cs_gfx = gfx.gfx_id)
Additionally, you ask if you should use joins. You are in fact using joins, by virtue of having multiple tables in your FROM clause and specifying the join criteria in the WHERE clause. Changing this to use the JOIN ON syntax might be a little easier to read:
FROM sometable A
JOIN someothertable B
ON A.somefield = B.somefield
JOIN somethirdtable C
ON A.somefield = C.somefield
etc
Edit:
You also likely want to make the join where you expect the null value to be a left outer join:
SELECT * FROM
first_table a
LEFT OUTER JOIN second_table b
ON a.someValue = b.someValue
If there is no match in the join, the row from the left side will still be returned.