I'm working on northwind database.
I have to select the newest and the oldest order/orders (could be multiple with same date).
Is it possible without using subqueries and top 1, only by joining tables?
Using a CTE:
WITH orders_rnk AS (
SELECT *, RANK() OVER (ORDER BY order_date ASC) AS rnk
FROM orders
)
SELECT * from orders_rn WHERE rnk = 1;
Using a JOIN:
SELECT o.*
FROM orders AS o
LEFT OUTER JOIN orders AS o2
ON o.order_date > o2.order_date
WHERE o2.order_id IS NULL;
Yes you can use TOP 1 but add WITH TIES keyword.
link to MS documentation
Per MS documentation
WITH TIES Returns two or more rows that tie for last place in the
limited results set. You must use this argument with the ORDER BY
clause. WITH TIES might cause more rows to be returned than the value
specified in expression. For example, if expression is set to 5 but
two additional rows match the values of the ORDER BY columns in row 5,
the result set will contain seven rows.
Exmaple
SELECT TOP 1 WITH TIES
FROM tableA A JOIN TableB
ON A.ID=B.ID
ORDER BY A.column1
Related
I want to execute this query in my database.As you can see both tables A and B has one-many relations ,but i need the latest record in B.so i here is my query :
select *,(select top 1 ResultTest ,ResultState2 from B where GasReceptionId=A.Id order by Id desc)
from A where OrganizationGasId= 4212
But i get this error
Msg 116, Level 16, State 1, Line 2
Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.
You can rephrase this query as a basic join which uses an analytic function (e.g. row number) to identify the correct row's data from B to include with each record coming from the A table.
SELECT *
FROM
(
SELECT a.*, b.ResultTest, b.ResultState2,
ROW_NUMBER() OVER (PARTITION BY a.Id ORDER BY a.ID DESC) rn
FROM A a
LEFT JOIN B b
ON a.Id = b.GasReceptionId
WHERE
a.OrganizationGasId = 4212
) t
WHERE t.rn = 1;
A subquery in the SELECT clause must return exactly one column (and one or zero rows). So you can either have two subqueries:
select
a.*,
(select top 1 resulttest from b where gasreceptionid = a.id order by id desc) as test,
(select top 1 resultstate2 from b where gasreceptionid = a.id order by id desc) as state
from a
where a.organizationgasid = 4212;
Or, much better, move the subquery to the FROM clause. One way is OUTER APPLY:
select
a.*, r.resulttest, r.resultstate2
from a
outer apply
(
select top 1 resulttest, resultstate2
from b
where gasreceptionid = a.id
order by id desc
) r
where a.organizationgasid = 4212;
Hi I have the below query in Teradata. I have a row number partition and from that I want rows with rn=1. Teradata doesn't let me use the row number as a filter in the same query. I know that I can put the below into a subquery with a where rn=1 and it gives me what I need. But the below snippet needs to go into a larger query and I want to simplify it if possible.
Is there a different way of doing this so I get a table with 2 columns - one row per customer with the corresponding fc_id for the latest eff_to_dt?
select cust_grp_id, fc_id, row_number() over (partition by cust_grp_id order by eff_to_dt desc) as rn
from table1
Have you considered using the QUALIFY clause in your query?
SELECT cust_grp_id
, fc_id
FROM table1
QUALIFY ROW_NUMBER()
OVER (PARTITION BY cust_grp_id
ORDER BY eff_to_dt desc)
= 1;
Calculate MAX eff_to_dt for each cust_grp_id and then join result to main table.
SELECT T1.cust_grp_id,
T1.fc_id,
T1.eff_to_dt
FROM Table1 AS T1
JOIN
(SELECT cust_grp_id,
MAX(eff_to_dt) AS max_eff_to_dt
FROM Table
GROUP BY cust_grp_id) AS T2 ON T2.cust_grp_id = T1.cust_grp_id
AND T2.max_eff_to_dt = T1.eff_to_dt
You can use a pair of JOINs to accomplish the same thing:
INNER JOIN My_Table T1 ON <some criteria>
LEFT OUTER JOIN My_Table T2 ON <some criteria> AND T2.eff_to_date > T1.eff_to_date
WHERE
T2.my_id IS NULL
You'll need to sort out the specific criteria for your larger query, but this is effectively JOINing all of the rows (T1), but then excluding any where a later row exists. In the WHERE clause you eliminate these by checking for a NULL value in a column that is NOT NULL (in this case I just assumed some ID value). The only way that would happen is if the LEFT OUTER JOIN on T2 failed to find a match - i.e. no rows later than the one that you want exist.
Also, whether or not the JOIN to T1 is LEFT OUTER or INNER is up to your specific requirements.
I need to build a query with a order by and rownum but without use a sublect.
It is needed to get the first row of the query ordered.
In other words, I want the result of
select * from (
SELECT CAMP1,ORDERCAMP
FROM TABLENAME
ORDER BY ORDERCAMP) where rownum=1;
but whithout use a subselect. Is it possible?
I have a Oracle 11. You could say this is my whole query:
SELECT T1.CAMP_ID,
T2.CAMP
(SELECT OT.CAMP
FROM OTHERTABLE OT
WHERE OT.FK_TO_TABLE1=T1.CAMP_ID
ORDER BY OT.ORDERCAMP
)
FROM TABLE1 T1,
TABLE2 T2
WHERE T1.FK_TO_T2=T2.PK;
The subquery returns more than one row, and I cant use another subquery like
SELECT T1.CAMP_ID,
T2.CAMP
(SELECT *
FROM
(SELECT OT.CAMP
FROM OTHERTABLE OT
WHERE OT.FK_TO_TABLE1=T1.CAMP_ID
ORDER BY OT.ORDERCAMP
)
WHERE ROWNUM=1
)
FROM TABLE1 T1,
TABLE2 T2
WHERE T1.FK_TO_T2=T2.PK;
SELECT CAMP1,ORDERCAMP FROM TABLE2 ORDER BY ORDERCAMP
Because the T1.CAMP_ID is an invalid identifier in the third level subquery.
I hope I have explained myself enough.
Your current query (without the invalid ORDER BY) gets ORA-01427: single-row subquery returns more than one row. You can nest subqueries, but you can only refer back one level when joining; so if you did:
SELECT T1.CAMP_ID, T2.CAMP,
(SELECT CAMP FROM
FROM
(SELECT OT.CAMP
FROM OTHERTABLE OT
WHERE OT.FK_TO_TABLE1=T1.CAMP_ID
ORDER BY OT.ORDERCAMP
)
WHERE ROWNUM = 1)
FROM TABLE1 T1, TABLE2 T2 WHERE T1.FK_TO_T2=T2.PK;
... then you would get ORA-00904: "T1"."CAMP_ID": invalid identifier. Hence your question, presumably.
What you could do instead is join to the third table, and use the analytic ROW_NUMBER() function to assign the row number, and then use an outer select wrapped around the whole thing to only find the records with the lowest ORDERCAMP:
SELECT CAMP_ID, CAMP, OT_CAMP
FROM (
SELECT T1.CAMP_ID, T2.CAMP, OT.CAMP AS OT_CAMP,
ROW_NUMBER() OVER (PARTITION BY T1.CAMP_ID ORDER BY OT.ORDERCAMP) AS RN
FROM TABLE2 T2
JOIN TABLE1 T1 ON T1.FK_TO_T2=T2.PK
JOIN OTHERTABLE OT ON OT.FK_TO_TABLE1=T1.CAMP_ID
)
WHERE RN = 1;
The ROW_NUMBER() can partition on the T1.CAMP_ID primary key value, or anything else that is unique.
SQL Fiddle demo, including the inner query run on its own so you can see the RN numbers assigned before the outer filter is applied.
Another approach is to use the aggregate KEEP DENSE_RANK FIRST function
SELECT T1.CAMP_ID, T2.CAMP,
MAX(OT.CAMP) KEEP (DENSE_RANK FIRST ORDER BY OT.ORDERCAMP) AS OT_CAMP
FROM TABLE2 T2
JOIN TABLE1 T1 ON T1.FK_TO_T2=T2.PK
JOIN OTHERTABLE OT ON OT.FK_TO_TABLE1=T1.CAMP_ID
GROUP BY T1.CAMP_ID, T2.CAMP;
Which is a bit shorter and doesn't need an inner query. I'm not sure if there's any real advantage of one over the other.
SQL Fiddle demo.
In the most recent version of Oracle, you can do:
SELECT CAMP1, ORDERCAMP
FROM TABLENAME
ORDER BY ORDERCAMP
FETCH FIRST 1 ROWS ONLY;
Otherwise, I think you need a subquery of some sort.
You could use LIMIT or SELECT TOP 1
SELECT CAMP1, ORDERCAMP FROM TABLENAME ORDER BY ORDERCAMP LIMIT 1
I'm writing a page that will create a query (for non-db users) and it create the query and run it returning the results for them.
I am using row_number to handle custom pagination.
How do I do a left join and a row_number in a subquery when I don't know the specific columns I need to return. I tried to use * but I get an error that
The column '' was specified multiple times
Here is the query I tried:
SELECT * FROM
(SELECT ROW_NUMBER() OVER (ORDER BY Test) AS ROW_NUMBER, *
FROM table1 a
LEFT JOIN table2 b
ON a.ID = b.ID) x
WHERE ROW_NUMBER BETWEEN 1 AND 50
Your query is going to fail in SQL Server regardless of the row_number() call. The * returns all columns, including a.id and b.id. These both have the same name. This is fine for a query, but for a subquery, all columns need distinct names.
You can use row_number() for an arbitrary ordering by using a "subquery with constant" in the order by clause:
SELECT * FROM
(SELECT ROW_NUMBER() OVER (ORDER BY (select NULL)) AS ROW_NUMBER, *
FROM table1 a
LEFT JOIN table2 b
ON a.ID = b.ID) x
WHERE ROW_NUMBER BETWEEN 1 AND 50 ;
This removes the dependency on the underlying column name (assuming none are named ROW_NUMBER).
Try this sql. It should work.
SELECT * FROM
(SELECT ROW_NUMBER() OVER (ORDER BY a.Test) AS ROW_NUMBER, a.*,b.*
FROM table1 a
LEFT JOIN table2 b
ON a.ID = b.ID) x
WHERE ROW_NUMBER BETWEEN 1 AND 50
So I think I've seen a solution to this however they are all very complicated queries. I'm in oracle 11g for reference.
What I have is a simple one to many join which works great however I don't need the many. I just want the left table (the one) to just join any 1 row which meets the join criteria...not many rows.
I need to do this because the query is in a rollup which COUNTS so if I do the normal left join I get 5 rows where I only should be getting 1.
So example data is as follows:
TABLE 1:
-------------
TICKET_ID ASSIGNMENT
5 team1
6 team2
TABLE 2:
-------------
MANAGER_NAME ASSIGNMENT_GROUP USER
joe team1 sally
joe team1 stephen
joe team1 louis
harry team2 ted
harry team2 thelma
what I need to do is join these two tables on ASSIGNMENT=ASSIGNMENT_GROUP but only have 1 row returned.
when I do a left join I get three rows returned beaucse that is the nature of hte left join
If oracle supports row number (partition by) you can create a sub query selecting where row equals 1.
SELECT * FROM table1
LEFT JOIN
(SELECT *
FROM (SELECT *,
ROW_NUMBER()
OVER(PARTITION BY assignmentgroup ORDER BY assignmentgroup) AS Seq
FROM table2) a
WHERE Seq = 1) v
ON assignmet = v.assignmentgroup
You could do something like this.
SELECT t1.ticket_id,
t1.assignment,
t2.manager_name,
t2.user
FROM table1 t1
LEFT OUTER JOIN (SELECT manager_name,
assignment_group,
user,
row_number() over (partition by assignment_group
--order by <<something>>
) rnk
FROM table2) t2
ON ( t1.assignment = t2.assignment_group
AND t2.rnk = 1 )
This partitions the data in table2 by assignment_group and then arbitrarily ranks them to pull one arbitrary row per assignment_group. If you care which row is returned (or if you want to make the row returned deterministic) you could add an ORDER BY clause to the analytic function.
I think what you need is to use GROUP BY on the ASSIGNMENT_GROUP field.
http://www.w3schools.com/sql/sql_groupby.asp
In MySQL you could just GROUP BY ASSIGNMENT and be done. Oracle is more strict and refuses to just choose (in an undefined way) which values of the three rows to choose. That means all returned columns need to be part of GROUP BY or be subject to an aggregat function (COUNT, MIN, MAX...)
You can of course choose to just don't care and use some aggregat function on the returned columns.
select TICKET_ID, ASSIGNMENT, MAX(MANAGER_NAME), MAX(USER)
from T1
left join T2 on T1.ASSIGNMENT=T2.ASSIGNMENT_GROUP
group by TICKET_ID, ASSIGNMENT
If you do that I would seriously doubt that you need the JOIN in the first place.
MySQL could also help with GROUP_CONCAT in the case that you want a string concatenation of group values for a column (humans often like that), but with Oracle that is staggeringly complex.
Using a subquery as already suggested is an option, look here for an example. It also allows you to sort the subquery before selecting the top row.
In Oracle, if you want 1 result, you can use the ROWNUM statement to get the first N values of a query e.g.:
SELECT *
FROM TABLEX
WHERE
ROWNUM = 1 --gets the first value of the result
The problem with this single query is that Oracle never returns the data in the same order. So, you must oder your data before use rownum:
SELECT *
FROM
(SELECT * FROM TABLEX ORDER BY COL1)
WHERE
ROWNUM = 1
For your case, looks like you only need 1 result, so your query should look like:
SELECT *
FROM
TABLE1 T1
LEFT JOIN
(SELECT *
FROM TABLE2 T2 WHERE T1.ASSIGNMENT = T2.ASSIGNMENT_GROUP
AND
ROWNUM = 1) T3 ON T1.ASSIGNMENT = T3.ASSIGNMENT_GROUP
you can use subquery - select top 1