I'm having some hard time doing the join function on those two tables. I have simplified the example dataset as there are additional where-clauses involved for the first table however that doesn't seem to be a problem.
I would write the query for joining the two tables below:
select a.prod_code, a.prod_name, b.ref_value from Product_code a
left join Product_reference b on a.prod_code = b.pref_code
where a.prod_code <> 'CURTAIN' and b.ref_value = 'MAN'
The problem I'm facing is that I want to join tables kind of conditionally. I.e. if the ref_type value is 'MAN' in Product_reference table, I do want to join it, otherwise not.
For an example this query would not include "Chair" in the result as it does not have an ref_type 'MAN' available in the "Product_name". What I'd need though is still show it in the query result, just without joined value from the Product_reference table (given that value with ref_type 'MAN' does not exist for it), not leave it out altogether.
Meanwhile Product_name table record 'CURTAIN' should be left off (regardless if Product_reference ref_type 'MAN' exists or not)
Any recommendations?
Product_code
prod_code prod_name
A Table
B Chair
C Window
D Door
E Curtain
Product_reference
pref_code ref_type ref_value
A MAN x
A AUTO y
B AUTO z
C AUTO z1
C MAN x1
D AUTO zxc
E AUTO abc
E MAN cba
Move b.ref_value = 'MAN' to the join predicate:
SELECT a.prod_code, a.prod_name, b.ref_value
FROM Product_code a
LEFT JOIN Product_reference b ON a.prod_code = b.pref_code AND b.ref_value = 'MAN'
WHERE a.prod_code <> 'CURTAIN'
This will accomplish what you want, which is only left joining the data from table b where b.ref_value = 'MAN', instead of removing all other rows from the result set altogether.
Side note, thanks for including your query and sample data in your very well made question. We appreciate it.
you could use a inner join on the distinct product that have 'MAN'
select
a.prod_code
, a.prod_name
, b.ref_value
from Product_code a
inner join (
select distinct pref_code
from Product_reference
where ref_type = 'MAN') t2 on t2.pref_code = a.prod_code
and a.prod_code <> 'CURTAIN'
Related
I have sql query where I have to join three tables. One of this is a table with data of invoice, it looks like this:
INVOICE
ID CUSTOMER_NAME TAXID NUMBER LABEL GUID
1 CUSTOMER1 8739281100 FV001/2019 1 04EABFB3-0B9D-4749-B99D-A4EBEE079633
POSITION OF INVOICE
ID ID_INV POSITION_NAME COUNT
1 1 NAME1 3
2 1 NAME2 2,5
TABLE WITH LABEL
ID NAME VALUE GUID_INV
1 LABEL1 true 04EABFB3-0B9D-4749-B99D-A4EBEE079633
When I want to run this query I have statement like this multiple rows in singleton select.
This is for Firebird 2.5.
SELECT
a.ID,
a.GUID,
a.NUMBER,
a.CUSTOMER_NAME,
b.COUNT,
(select usrd.LABEL from USER_FIELD_DEFS usrd
where usrd.GUID_INV=a.GUID and (usrd.ID=1 and usrb.VALUE='true')) as LABEL_NAME
FROM INVOICE a
join POSITION_INVOICE b ON a.ID=b.ID_INV
I want to get result like this
1 04EABFB3-0B9D-4749-B99D-A4EBEE079633 FV001/2019 CUSTOMER1 3 LABEL1
1 04EABFB3-0B9D-4749-B99D-A4EBEE079633 FV001/2019 CUSTOMER1 2,5 LABEL1
Please help with this. I know that solution maybe is very simple but I have some eclipse of the mind:)
This should give you the rows you want based on the 3 tables you provided. If there is a chance that an invoice has no position then simply replace the inner join with left join
SELECT
I.[Id]
,I.[GUID]
,I.[NUMBER]
,I.[CUSTOMER_NAME]
,IP.[POSITION_NAME]
,L.[NAME]
FROM [INVOICE] I
INNER JOIN [IN_P] IP ON IP.ID_INV = I.Id
LEFT JOIN [LABEL] L ON L.[GUID_INV] = I.[GUID]
You are just missing one more join here. Assuming USER_FIELD_DEFS is the same as TABLE WITH LABEL that you have mentioned here
SELECT
a.ID,
a.GUID,
a.NUMBER,
a.CUSTOMER_NAME,
b.COUNT,
c.NAME
FROM INVOICE a
JOIN POSITION_INVOICE b ON a.ID=b.ID_INV
JOIN USER_FIELD_DEFS c ON c.GUID_INV = a.GUID AND c.ID=1 and c.VALUE='true'
I have two tables customer_details and address_details. I want to display customer details with their corresponding address, so I was using a LEFT JOIN, but when I'm executing this query, SQL Server drops rows where street_no of customer_details table doesn't match with the street_no in address_detials table and displays only rows where `street_no' of customer_detials = street_no of address_details table. I need to display a complete customer_details table and in case if street_no doesn't matches it should display empty string or anything. Am I doing anything wrong in my SQL join?
Table customer_details:
case_id customer_name mob_no street_no
-------------------------------------------------
1 John 242342343 4324234234234
1 Rohan 343233333 43332
1 Ankit 234234233 2342332423433
1 Suresh 234234324 2342342342342
1 Ranjeet 343424323 32233
1 Ramu 234234333 2342342342343
Table address_details:
s_no streen_no address city case_id
------------------------------------------------------
1 4324234234234 Roni road Delhi 1
2 2342332423433 Natan street Lucknow 1
3 2342342342342 Koliko road Herdoi 1
SQL JOIN query:
select
a.*, b.address
from
customer_details a
left join
address_details b on a.street_no = b.street_no
where
b.case_id = 1
Now that it became clear that you used b.case_id=1, I will explain why it filters:
The LEFT JOIN itself returns some rows that contain all NULL values for table b in the result set, which is what you want and expect.
But by using WHERE b.case_id=1, the rows containing NULL values for table b are filtered out because none of them matches the condition (all those rows have b.case_id=NULL so they don't match).
It might work to instead use WHERE a.case_id=1, but we don't know if a.case_id and b.case_id are always the same value for matching rows (they might not be; and if they are always the same, then we just identified a potential redundancy).
There are two ways to fix this for sure.
(1) Move b.case_id = 1 into the left join condition:
left join address_details b on a.street_no = b.street_no and b.case_id = 1
(2) Keep b.case_id = 1 in the WHERE but also allow for NULLED-out b values:
left join address_details b on a.street_no = b.street_no
where b.case_id = 1
or b.street_no IS NULL
Personally I'd go for (1) because that is the most clear way to express that you want to filter b on two conditions, without affecting the rows of a that are being returned.
I do think that Wilhelm Poggenpohl answer is kind of right. You just need to change the last join condition a.case_id=1 to b.case_id=1
select a.* , b.address
from customer_details a
left join address_details b on a.street_no=b.street_no
and b.case_id=1
This query will show every row from customer_details and the corresponding adress if there is a match of street_no and the adress meets the condition case_id=1.
This is because of the where clause. Try this:
select a.* , b.address
from customer_details a
left join address_details b on a.street_no=b.street_no
and a.case_id=1
How to find city when ContactID is provided and condition is if ContactID is coming as 123 then it will look whether it is P or C, If P then it will go to Person table and returns City(USA) as output and If C then it will go to Company table and gives City(AUS) as output.
NB: all tables contain thousands of record and City value comes from run time.
Unless you're dynamically generating the query (i.e. using some language other than SQL to execute it) then you need to join on both tables anyway. If you're joining on both tables then there's no need for a CASE statement:
select *
from contacts co
left outer join person p
on co.contactid = p.contactid
and co.person_company = 'P'
left outer join company c
on co.contactid = c.contactid
and co.person_company = 'C'
You'll start noting an issue here, for every column from PERSON and COMPANY you're going to have to add some business logic to work out which table you want the information from. This can get very tiresome
select co.contactid
, case when p.id is not null then p.name else c.name end as name
from contacts co
left outer join person p
on co.contactid = p.contactid
and co.person_company = 'P'
left outer join company c
on co.contactid = c.contactid
and co.person_company = 'C'
Your PERSON and COMPANY tables seem to have exactly the same information in them. If this is true in your actual data model then there's no need to split them up. You make the determination as to whether each entity is a person or a company in your CONTACTS table.
Creating additional tables to store data in this manner is only really helpful if you need to store additional data. Even then, I'd still put the data that means the same thing for a person or a companny (i.e. name or address) in a single table.
If there's a 1-2-1 relationship between CONTACTID and PID and CONTACTID and CID, which is what your sample data implies, then you have a number of additional IDs, which have no value.
Lastly, if you're not restricting that only companies can go in the COMPANY table and individuals in the PERSON table. You need the PERSON_COMPANY column to exist in both PERSON and COMPANY, though as a fixed string. It would be more normal to set up this data model as something like the following:
create table contacts (
id integer not null
, contact_type char(1) not null
, name varchar2(4000) not null
, city varchar2(3)
, constraint pk_contacts primary key (id)
, constraints uk_contacts unique (id, contact_type)
);
create table people (
id integer not null
, contact_type char(1) not null
, some_extra_info varchar2(4000)
, constraint pk_people primary key (id)
, constraint fk_people_contacts
foreign key (id, contact_type)
references contacts (id, contact_type)
, constraint chk_people_type check (contact_type = 'P')
);
etc.
you can LEFT JOIN all 3 tables and the using a CASE statement select the one that you need based on the P or C value
SELECT
CASE c.[Person/Company]
WHEN 'P' THEN p.NAME
WHEN 'C' THEN a.Name
END AS Name
FROM Contact c
LEFT JOIN Person p on p.ContactId = c.ContactId
LEFT JOIN Company a on a.ContachId = c.ContactId
Ben's answer is almost right. You might want to check that the first join has no match before doing the second one:
select c.*, coalesce(p.name, c.name) as p.name
from contacts c left outer join
person p
on c.contactid = p.contactid and
c.person_company = 'P' left join
company co
on c.contactid = co.contactid and
c.person_company = 'C' and
p.contactid is null;
This may not be important in your case. But in the event that the second join matches multiple rows and the first matches a single row, you might not want the additional rows in the output.
I created a database in ms sql , in the database I have three category of persons namely staff, customers, suppliers whom I stored in different tables create serial unique id for each.
Now these persons id are stored under person_id and a column names person type which stores whether its a staff, custimer or supplier in the transaction table, The problem lies in selecting the records from the transaction table like this pseudo code
Select t.*,s.na as staff,sp.name as supplier, c.name as customer
From Trans t
left join Staff s on s.id = t.pid
left join Suppliers sp on sp.id = t.pid
left join Customers c on c.id = t.pid
This returns one row, instead of at least 3 or more, How do I solve this problem
My trans table
person_id Person_type Trans_id
1 staff 1
1 customer 2
2 customer 3
3 suppler 4
1 staff 5
Expected output
person_name Trans_id
james 1
mark 2
dan 3
jude 4
james 5
Staff, Customers, and suppliers are stored in their different tables
That's what the Join does, combine data from multiple tables into one result row. If you want to "keep the rows", not combine them, you can use UNION
(
Select t.* From Trans t
left join Staff s on s.id = t.pid
)
UNION
(
Select t.* From Trans t
left join Suppliers sp on sp.id = t.pid
)
UNION
(
Select t.* From Trans t
left join Customers c on c.id = t.pid
)
This will get you the multiple rows you want BUT still not sure you have defined it right. I see you are only taking columns from Trans, so you're not getting any data from the other tables. And you're doing left outer joins so the other tables won't affect the selection. So I think it's just that same as selecting from just Trans.
If what you want is data from Trans where there is corresponding entry in the other tables, then do the UNION, but also change the outer joins to inner.
Hi Guys I have a table relation which works like this (legacy)
A has many B and B has many C;
A has many C as well
Now I am having trouble coming up with a SQL which will help me to get all B (Id of B to make it simple) mapped to certain A(by Id) AND any B which has a collection of C that's a subset of Cs of that A.
I have failed to come up with a decent sql specially for the second part and was wondering if I can get any tips / suggestions re how I can do that.
Thanks
EDIT:
Table A
Id |..
------------
1 |..
Table B
Id |..
--------------
2 |..
Table A_B_rel
A_id | B_id
-----------------
1 | 2
C is a strange table. The data of C (single column) is actually just duped in 2 rel table for A and B. so its like this
Table B_C_Table
B_Id| C_Value
-----------------
2 | 'Somevalue'
Table A_C_Table
A_Id| C_Value
-------------
1 | 'SomeValue'
So I am looking for Bs the C_Values of which are subset of certain A_C_Values.
Yes, the second part of your problem is a bit tricky. We've got B_C_Table on the one hand, and a subset of A_C_Table where A_ID is a specific ID, on the other.
Now, if we use an outer join, we'll be able to see which rows in B_C_Table have no match in A_C_Table:
SELECT *
FROM B_C_Table bc
LEFT JOIN A_C_Table ac ON bc.C_Value = ac.C_Value AND ac.A_ID = #A_ID
Note that it is important to put the ac.A_ID = #A_ID into the ON clause rather than into WHERE, because in the latter case we would be filtering out non-matching rows of #A_ID, which is not what we want.
The next step (to achieving the final query) would be to group rows by B and count rows. Now, we will calculate both the total number of rows and the number of matching rows.
SELECT
bc.B_ID,
COUNT(*) AS TotalCount,
COUNT(ac.A_ID) AS MatchCount
FROM B_C_Table bc
LEFT JOIN A_C_Table ac ON bc.C_Value = ac.C_Value AND ac.A_ID = #A_ID
GROUP BY bc.B_ID
As you can see, to count matches, we simply count ac.A_ID values: in case of no match the corresponding column will be NULL and thus not counted. And if indeed some rows in B_C_Table do not match any rows in the subset of A_C_Table, we will see different values of TotalCount and MatchCount.
And that logically leads us towards the final step: comparing those counts. (For, obviously, if we can obtain values, we can also compare them.) But not in the WHERE clause, of course, because aggregate functions aren't allowed in WHERE. It's the HAVING clause that is used to compare values of grouped rows, including aggregated values too. So...
SELECT
bc.B_ID,
COUNT(*) AS TotalCount,
COUNT(ac.A_ID) AS MatchCount
FROM B_C_Table bc
LEFT JOIN A_C_Table ac ON bc.C_Value = ac.C_Value AND ac.A_ID = #A_ID
GROUP BY bc.B_ID
HAVING COUNT(*) = COUNT(ac.A_ID)
The count values aren't really needed, of course, and when you drop them you will be able to UNION the above query with the one selecting B_ID from A_B_rel:
SELECT B_ID
FROM A_B_rel
WHERE A_ID = #A_ID
UNION
SELECT bc.B_ID
FROM B_C_Table bc
LEFT JOIN A_C_Table ac ON bc.C_Value = ac.C_Value AND ac.A_ID = #A_ID
GROUP BY bc.B_ID
HAVING COUNT(*) = COUNT(ac.A_ID)
Sounds like you need to think in terms of double negation, i.e. there should not exist any B_C that does not have a matching A_C (and I'm guessing there should be at least one B_C).
So, try something like
select B.B_id
from Table_B B
where exists (select 1 from B_C_Table BC
where BC.B_id = B.B_id)
and not exists (select 1 from B_C_Table BC
where BC.B_id = B.B_id
and not exists(select 1 from B_C_Table AC
join A_B_Rel ABR on AC.A_id = ABR.A_id
where ABR.B_id = B.B_id
and BC.C_Value = AC.C_Value))
Perhaps this is what you're looking for:
SELECT B_id
FROM A_B_rel
WHERE A_id = <A ID>
UNION
SELECT a.B_Id
FROM B_C_Table a
LEFT JOIN A_C_Table b ON a.C_Value = b.C_Value AND b.A_Id = <A ID>
GROUP BY a.B_Id
HAVING COUNT(CASE WHEN b.A_Id IS NULL THEN 1 END) = 0
The first SELECT gets all B's which are mapped to a particular A (<A ID> being the input parameter for the A ID), then we tack onto that result set any additional B's whose entire set of C_Value's are within the subset of the C_Value's of the particular A (again, <A ID> being the input parameter).