I have a database where I am trying to group together similar column values and display the NULL values as separate entries.
Currently I have the following:
SELECT i.*, IFNULL(iset.set_id, UUID()) AS the_set FROM img_ref i
LEFT JOIN image_set iset ON iset.img_id = i.id
GROUP BY the_set
This works, provided there are entries in the image_set table. If there are no entries in that table, it simply groups together all the NULL values. If I remove the 'group by' statement, I get the individual rows with the unique identifier, different in each case.
Its unlikely that the image_set table would be empty, but if it was all the 'separate' images would be grouped together as one entry instead of multiple ones.
Is there something that I'm doing wrong in the query?
You have to subquery it first before using the derived UUIDs
SELECT *
FROM (
SELECT i.*, IFNULL(iset.set_id, UUID()) AS the_set FROM img_ref i
LEFT JOIN image_set iset ON iset.img_id = i.id
) SQ
GROUP BY the_set
Related
To begin with, I have a table in my db that is fed with SalesForce info. When I run this example query it returns 2 rows:
select * from SalesForce_INT_Account__c where ID_SAP_BAYER__c = '3783513'
When I run this next query on the same table I obtain one of the rows, which is what I need:
SELECT MAX(ID_SAP_BAYER__c) FROM SalesForce_INT_Account__c where ID_SAP_BAYER__c = '3783513' GROUP BY ID_SAP_BAYER__c
Now, I have another table (PedidosEspecialesZarateCabeceras) which has a field (NroClienteDireccionEntrega) that I can match with the field I've been using in the SalesForce table (ID_SAP_BAYER__c). This table has a key that consists of just 1 field (NroPedido).
What I need to do is join these 2 tables to obtain a row from PedidosEspecialesZarateCabeceras with additional fields coming from the SalesForce table, and in case those additional fields are not available, they should come as NULL values, so for that im using a LEFT OUTER JOIN.
The problem is, since I have to match NroClienteDireccionEntrega and ID_SAP_BAYER__c and there's 2 rows in the salesforce table with the same ID_SAP_BAYER__c, my query returns 2 duplicate rows from PedidosEspecialesZarateCabeceras (They both have the same NroPedido).
This is an example query that returns duplicates:
SELECT
cab.CUIT AS CUIT,
convert(nvarchar(4000), cab.NroPedido) AS NroPedido,
sales.BillingCity__c as Localidad,
sales.BillingState__c as IdProvincia,
sales.BillingState__c_Desc as Provincia,
sales.BillingStreet__c as Calle,
sales.Billing_Department__c as Distrito,
sales.Name as RazonSocial,
cab.NroCliente as ClienteId
FROM PedidosEspecialesZarateCabeceras AS cab WITH (NOLOCK)
LEFT OUTER JOIN
SalesForce_INT_Account__c AS sales WITH (NOLOCK) ON
cab.NroClienteDireccionEntrega = sales.ID_SAP_BAYER__c
and sales.ID_SAP_BAYER__c in
( SELECT MAX(ID_SAP_BAYER__c)
FROM SalesForce_INT_Account__c
GROUP BY ID_SAP_BAYER__c
)
WHERE cab.NroPedido ='5320'
Even though the join has MAX and Group By, this returns 2 duplicate rows with different SalesForce information (Because of the 2 salesforce rows with the same ID_SAP_BAYER__c), which should not be possible.
What I need is for the left outer join in my query to pick only ONE of the salesforce rows to prevent duplication like its happening right now. For some reason the select max with the group by is not working.
Maybe I should try to join this tables in a different way, can anyone give me some other ideas on how to join the two tables to return just 1 row? It doesnt matter if the SalesForce row that gets picked out of the 2 isn't the correct one, I just need it to pick one of them.
Your IN clause is not actually doing anything, since...
SELECT MAX(ID_SAP_BAYER__c)
FROM SalesForce_INT_Account__c
GROUP BY ID_SAP_BAYER__c
... returns all possible IDSAP_BAYER__c values. (The GROUP BY says you want to return one row per unique ID_SAP_BAYER__c and then, since your MAX is operating on exactly one unique value per group, you simply return that value.)
You will want to change your query to operate on a value that is actually different between the two rows you are trying to differentiate (probably the MAX(ID) for the relevant ID_SAP_BAYER__c). Plus, you will want to link that inner query to your outer query.
You could probably do something like:
...
LEFT OUTER JOIN
SalesForce_INT_Account__c sales
ON cab.NroClienteDireccionEntrega = sales.ID_SAP_BAYER__c
and sales.ID in
(
SELECT MAX(ID)
FROM SalesForce_INT_Account__c sales2
WHERE sales2.ID_SAP_BAYER__c = cab.NroClienteDireccionEntrega
)
WHERE cab.NroPedido ='5320'
By using sales.ID in ... SELECT MAX(ID) ... instead of sales.ID_SAP_BAYER__c in ... SELECT MAX(ID_SAP_BAYER__c) ... this ensures you only match one of the two rows for that ID_SAP_BAYER__c. The WHERE sales2.ID_SAP_BAYER__c = cab.NroClienteDireccionEntrega condition links the inner query to the outer query.
There are multiple ways of doing the above, especially if you don't care which of the relevant rows you match on. You can use the above as a starting point and make it match your preferred style.
An alternative might be to use OUTER APPLY with TOP 1. Something like:
SELECT
...
FROM PedidosEspecialesZarateCabeceras AS cab
OUTER APPLY(
SELECT TOP 1 *
FROM SalesForce_INT_Account__c s1
WHERE cab.NroClienteDireccionEntrega = s1.ID_SAP_BAYER__c
) sales
WHERE cab.NroPedido ='5320'
Without an ORDER BY the match that TOP 1 chooses will be arbitrary, but I think that's what you want anyway. (If not, you could add an ORDER BY).
I imagine this is a really basic oversight on my part but I have an SQL query which works fine. But I when I SELECT from that result (SELECT FROM (SELECT))
I get a 'duplicate column' error. There are duplicate column names, for sure, in two tables where I compare them but they do not cause a problem in the initial result. For example:
SELECT _dia_tagsrel.tag_id,_dia_tagsrel.article_id, _dia_tags.tag_id, _dia_tags.tag
FROM _dia_tagsrel
JOIN _dia_tags
ON _dia_tagsrel.tag_id = _dia_tags.tag_id
Works fine but when I try to select from it, I get the error:
SELECT DISTINCT tag FROM
(SELECT _dia_tagsrel.tag_id,_dia_tagsrel.article_id, _dia_tags.tag_id, _dia_tags.tag
FROM _dia_tagsrel
JOIN _dia_tags
ON _dia_tagsrel.tag_id = _dia_tags.tag_id) a
Regardless of the DISTINCT. Ok, I can change the column names to be unique but the question really is - why do i get the error when I SELECT FROM (SELECT) and not in the initial query?
Thanks
Solution:
SELECT DISTINCT tag_id, tag FROM (SELECT _dia_tagsrel.tag_id, _dia_tagsrel.article_id, _dia_tags.tag
FROM _dia_tagsrel
JOIN _dia_tags
ON _dia_tagsrel.tag_id = _dia_tags.tag_id) a
I only needed to SELECT one of the duplicate columns, even though I was comparing the both of them. Provided by answer below.
In you are second query i.e., the sub query, you are selecting tag_id twice. Though it is from two different tables, it works out whey you are selecting the data. But when you select the columns with same name twice, it provides you duplicate error. Below is the way you have selected the column which is incorrect
_dia_tagsrel.tag_id,_dia_tagsrel.article_id, _dia_tags.tag_id, _dia_tags.tag
While using sub queries, merge, in or exists clause, avoid using the same column names multiple times.
Simple join works out no need of having subquery,
SELECT _dia_tagsrel.tag_id,_dia_tagsrel.article_id, _dia_tags.tag_id, _dia_tags.tag
FROM _dia_tagsrel
JOIN _dia_tags
ON _dia_tagsrel.tag_id = _dia_tags.tag_id
Your first query returns four columns:
tag_id
article_id
tag_id
tag
Duplicate column names are allowed in a result set, but are not allowed in a table -- or derived table, view, CTE, or most subqueries (an exception are EXISTS subqueries).
I hope you can see the duplicate. There is no need to select tag_id twice, because the JOIN requires that the values are the same. So just select three columns:
SELECT tr.tag_id, tr.article_id, t.tag
FROM _dia_tagsrel tr JOIN
_dia_tags t
ON tr.tag_id = t.tag_id
Your subquery has two tag_ids, so how database engine decide which one you want to use.
So, either use one (join requires tag_ids to be same) or re-name it :
If _dia_tag has unique tags then you can use EXISTS instead of INNER JOIN:
SELECT t.tag
FROM _dia_tags t
WHERE EXISTS (SELECT 1 FROM _dia_tagsrel tr WHERE tr.tag_id = t.tag_id);
I have the following query that uses joins to join multiple tables
select DISTINCT
tblArticles.Article_Title,
tblArticles.Article_img,
tblArticles.Article_Content,
tblArticles.Article_Date_Created,
tblArticles.Article_Sequence,
tblWriters.Writer_Name,
tblTypes.Article_Type_Name,
tblimages.image_path as "Extra images"
from tblArticles inner join tblWriters
on tblArticles.Writer_ID_Fkey = tblWriters.Writer_ID inner join
tblArticleType on tblArticles.Article_ID = tblArticleType.Article_ID_Fkey inner join
tblTypes on tblArticleType.Article_Type_ID_Fkey = tblTypes.Article_Type_ID left outer join tblExtraImages
on tblArticles.Article_ID = tblExtraImages.Article_ID_Fkey left outer join tblimages
on tblExtraImages.image_id_fkey = tblimages.image_id
order by tblArticles.Article_Sequence, tblArticles.Article_Date_Created;
And I get the following results:
If an article has more than one type_name then I will get repeated columns for the rest of the records. Is there another way of joining these tables that would prevent that from happening?
The simplest method is to just remove column Article_Type_Name from the select clause. This allows SELECT DISTINCT to identify the rows as duplicates, and eliminate them.
Another option is to use an aggregation function on the column. In recent SQL Server versions, STRING_AGG() comes handy (you can also use MIN() or MAX()):
select
tblArticles.Article_Title,
tblArticles.Article_img,
tblArticles.Article_Content,
tblArticles.Article_Date_Created,
tblArticles.Article_Sequence,
tblWriters.Writer_Name,
string_agg(tblTypes.Article_Type_Name, ',')
within group(order by tblTypes.Article_Type_Name) Article_Type_Name_List,
tblimages.image_path as Extra_Images
from ..
group by
tblArticles.Article_Title,
tblArticles.Article_img,
tblArticles.Article_Content,
tblArticles.Article_Date_Created,
tblArticles.Article_Sequence,
tblWriters.Writer_Name,
tblimages.image_path
What you're seeing here is a Cartesian product; you've joined Tables in such a way that multiple rows from one side match with rows from the other
If you don't care about the article_type, then group the other columns and take the max(article_type), or omit it in a subquery that selects distinct records, not including the article type column, from the table that contains article type). If your SQLS is recent enough and you want to know all the article types you could STRING_AGG them into a csv list
Ultimately what you choose to do depends on what you want them for; filter the rows out, or group them down
I have the following query and I try to keep a unique value for each GLOBAL_CONTENT_ID using the DISTINCT keyword. Unfortunately I cannot make it work.
SELECT DISTINCT
CD.GLOBAL_CONTENT_ID, CD.DOWNLOAD_ID, PA.PHYSICAL_ASSET_ID
FROM
[CONTENT_DOWNLOAD] CD
INNER JOIN
PHYSICAL_ASSET AS PA ON CD.GLOBAL_CONTENT_ID = PA.GLOBAL_CONTENT_ID
WHERE
CD.UPC = '00600753515501'
ORDER BY
CD.GLOBAL_CONTENT_ID
Any idea?
Thanks
The DISTINCT keyword will ensure that no duplicate records appear in your result set. However, it makes no guarantee that a given column cannot have duplicate values across multiple records, if the combination of values in those records be distinct.
One option to get the distinct GLOBAL_CONTENT_ID values would be to use the following query:
SELECT DISTINCT CD.GLOBAL_CONTENT_ID
FROM [CONTENT_DOWNLOAD] CD
INNER JOIN PHYSICAL_ASSET AS PA ON CD.GLOBAL_CONTENT_ID = PA.GLOBAL_CONTENT_ID
WHERE CD.UPC = '00600753515501'
ORDER BY CD.GLOBAL_CONTENT_ID
DISTINCT works on every column in the SELECT clause, not just a single column. If one of those columns has a different value, then the row is considered different and returned as another row. In your query, you are including 'PHYSICAL_ASSET_ID' which has a different value for each row which is why you are getting multiple rows.
I have combined two different tables together, one side is named DynDom and the other is CATH. I am trying to remove duplicates from that table such as below:
However, if i select distinct Dyndom pdbcode from the table, it returns distinct values of that pdbcode.
and
Based on the pictures above, I commented out the DynDom/CATH columns in the table and ran the query separately for DynDom/CATH and it returned those values accordingly, which is what i need and i was wondering if it's possible for me to use 2 distinct statements to return distinct values of the entire table based on the pdbcode.
Here's my code :
select DISTINCT
cath_dyndom_table_2."DYNDOM_DOMAINID",
cath_dyndom_table_2."DYNDOM_DSTART",
cath_dyndom_table_2."DYNDOM_DEND",
cath_dyndom_table_2."DYNDOM_CONFORMERID",
cath_dyndom_table_2.pdbcode,
cath_dyndom_table_2."DYNDOM_ChainID",
cath_dyndom_table_2.cath_pdbcode,
cath_dyndom_table_2."CATH_BEGIN",
cath_dyndom_table_2."CATH_END"
from
cath_dyndom_table_2
where
pdbcode = '2hun'
order by
cath_dyndom_table_2."DYNDOM_DOMAINID",
cath_dyndom_table_2."DYNDOM_DSTART",
cath_dyndom_table_2."DYNDOM_DEND",
cath_dyndom_table_2.pdbcode,
cath_dyndom_table_2.cath_pdbcode,
cath_dyndom_table_2."CATH_BEGIN",
cath_dyndom_table_2."CATH_END";
In the end, i would like to search domains from DynDom and CATH, based on the pdbcode and return the rows without having duplicate values.
Thank you.
UPDATE :
This is my VIEW table that i have done.
CREATE VIEW cath_dyndom_table AS
SELECT
r.domainid AS "DYNDOM_DOMAINID",
r.DomainStart AS "DYNDOM_DSTART",
r.Domain_End AS "DYNDOM_DEND",
r.ddid AS "DYN_DDID",
r.confid AS "DYNDOM_CONFORMERID",
r.pdbcode,
r.chainid AS "DYNDOM_ChainID",
d.cath_pdbcode,
d.cathbegin AS "CATH_BEGIN",
d.cathend AS "CATH_END"
FROM dyndom_domain_table r
FULL OUTER JOIN cath_domains d ON d.cath_pdbcode::character(4) = r.pdbcode
ORDER BY confid ASC;
What you are getting is the cartesian product of the ´two tables`.
In order to get one line without duplicates you need to have to have a 1-to-1 relation between both tables.
You can see HERE what are cartesian joins and HERE how to avoid them!
It sounds as though you want a UNION of domain name and ranges from each table - this can be achieved like so:
SELECT DYNDOM_DOMAINID, DYNDOM_DSTART, DYNDOM_DEND
FROM DynDom
UNION
SELECT RTRIM(cath_pdbcode), CATH_BEGIN, CATH_END
FROM CATH
This should eliminate exact duplicates (ie. where the domain name, start and end are all identical) but will not eliminate duplicate domain names with different ranges - if these exist you will need to decide how to handle them (retain them as separate entries, combine them with lowest start and highest end, or whatever other option is preferred).
EDIT: Actually, I believe you can get the desired results simply by changing the JOIN ON condition in your view to be:
FULL OUTER JOIN cath_domains d
ON d.cath_pdbcode::character(5) = r.pdbcode || r.chainid AND
r.DomainStart <= d.cathbegin AND
r.Domain_End >= d.cathend