I have three tables and two seperate SQL queries which are working correctly and I am having correct results.
If I try to join these three tables I am having null as result.
First query:
select T1.ID,T3.COMPANY
from T1,T3
where (T1.status!='CLOSED') and (T1.PRIORITY)>5 and T1.CLASSID=T3.CLASSID
Second query:
SELECT T1.ID, T2.DESCRIPTION
FROM T1
LEFT OUTER JOIN T2
ON T1.ID=T2.KEY
WHERE T1.status!='CLOSED'
AND (T2.CREATEDATE= (SELECT MAX(CREATEDATE)
FROM T2
WHERE T2.KEY=T1.ID))
I tried to join them but as result I am having null:
select T1.ID,T3.COMPANY,T2.DESCRIPTION
from T1
INNER JOIN T3 ON T1.CLASSID=T3.CLASSID
LEFT OUTER JOIN T2
ON T1.ID=T2.KEY
where (T1.status!='CLOSED') AND (T1.PRIORITY)>5
AND (T2.CREATEDATE= (SELECT MAX(CREATEDATE)
FROM T2
WHERE T2.KEY=T1.ID))
like it does not recognized last part for taking MAX value from T2 table.
What am I doing wrong? Thanks for help
Firstly, use an alias for the subquery on table T2.
T2.CREATEDATE =
(SELECT MAX(T2Alias.CREATEDATE)
FROM T2 AS T2Alias
WHERE T2Alias.KEY = T1.ID)
Secondly, consider moving this condition into the ON clause of the LEFT JOIN to table T2.
The first thing that jumps out at me is the new dependency on both T1.Priority > 5 and T2.CreateDate value being equal to the result of the inline query:
( AND (T1.PRIORITY) > 5
AND (T2.CREATEDATE =
(SELECT MAX(CREATEDATE) FROM T2 WHERE T2.KEY = T1.ID) )
Without the data it's difficult to check however this may be the issue
Related
I have 3 tables in BigQuery.
I need to join first one (contains ids), to others (contains list of values for ids). I want to have sum of values by ids from two tables:
SELECT t0.id, sum(values) FROM t0
LEFT JOIN t1 ON t0.id = t1.id
LEFT JOIN t2 ON t0.id = t2.id
GROUP BY id
It does not work with an error Column name values is ambiguous
What is the best way to make it?
SELECT t0.id, sum(t1.values) + sum(t2.values) as sumOfValues FROM t0
LEFT JOIN t1 ON t0.id = t1.id
LEFT JOIN t2 ON t0.id = t2.id
GROUP BY id
I think below better reflect your original idea
#standardSQL
SELECT id, sum(u.values)
FROM t0
LEFT JOIN (
SELECT id, values FROM t1 UNION ALL
SELECT id, values FROM t2
) u
USING (id)
GROUP BY id
I'm new to SQL. I need help with left join with an select.
The part I'm interested in:
Select...
from table t1
left join table t2
on t1.id=t2.id,
left join (select * from table 3 where ...) t3
on t1.id=t3.id
where t1.id='something'
Also i tried to moved in the where clause the t1.id(+)=t3.id but didn't work.
I think the logic you want is:
Select...
from t1 left join
t2
on t1.id = t2.id left join
t3
on t1.id = t3.id and
<t3 conditions go here>
where t1.id = 'something'
You have a superfluous comma -- and commas should never be in the FROM clause.
You also have a superfluous subquery. You can get the same functionality by just including the condition in the ON clause.
This is somewhat of a followon to SQL JOIN where to place the WHERE condition?
I would prefer to use the USING clause on the join, but am not yet able to put the field value condition with the join.
SELECT 1
FROM table1 t1
JOIN table2 t2 USING(id) AND t2.field = 0;
ORA-00933: SQL command not properly ended
Is it possible to have USING and another condition as part of the JOIN clause?
You can use:
SELECT 1
FROM table1 t1
JOIN table2 t2 USING(id)
WHERE t2.field = 0;
Using USING(id) is like using ON t1.id = t2.id except that in the JOIN result instead of two columns t1.id & t2.id there is only one id column.
For INNER JOIN USING with a condition followed by an OUTER JOIN you need a subquery to keep the WHERE with the USING:
SELECT ...
FROM (SELECT id, ...
FROM table1 t1
JOIN table2 t2 USING(id)
WHERE t2.field = 0) s
LEFT JOIN ...;
For an OUTER JOIN USING with a condition you need a subselect:
SELECT ...
FROM table1 t1
LEFT JOIN (SELECT *
FROM table2 t2
WHERE t2.field = 0) t2
USING (id);
See this re ON/WHERE with JOIN. See this re ON/WHERE when mixing INNER & OUTER JOINs.
I am try running this query and it takes long time because of the join i am using
SELECT T1.Id,T2.T2Id,T2.Col2
FROM Table1 T1
LEFT OUTER JOIN (SELECT TOP 1 Id, TT.T2Id,TT.Col2
FROM Table2 TT
WHERE TT.TypeId=3
ORDER BY TT.OrderId
)AS T2 ON T2 .Id=T1.Id
Thing is it doesn't let me do something like TT.Id=T1.Id with in the join query.
Is there any other way I can do this?
Try it with outer apply:
SELECT T1.Id, T2.T2Id, T2.Col2
FROM Table1 T1
OUTER APPLY (SELECT TOP 1 T2Id, T2.Col2
FROM Table2 TT
WHERE TT.TypeId = 3 AND TT.Id = T1.Id) T2
SELECT T1.Id, T2.T2Id, T2.Col2
FROM Table1 T1
OUTER APPLY (SELECT TOP 1 T2Id, T2.Col2
FROM Table2 TT
WHERE TT.TypeId = 3 AND T1.Id = TT.Id
Order by T2id desc) T2
I would use Outer Apply and T1.Id = TT.Id in the where condition since T1 is the parent table plus adding on order by - if needed for ordered result set
Well first of all your derived table will produce non deterministic results, as the top 1 row you return may differ each time you run it, even if the data in the table remains the same. You could put an order by clause in the the derived table to prevent that.
Is there an index on Table1.id? What exactly are you trying to achieve though, is it to return all rows from Table1, with just one row of many from Table2 that has the same ID?
If so I would look into using Cross Apply instead. Or maybe in this case Outer Apply. If I get a chance later I'll write up an example if needed, but in the mean time just Google Outer Apply for SQL Server.
Dan
I'm using Oracle 10, but the best way to ask this question is with an example.
select *
from t1, t2
where t1.id = t2.id
and t1.otherID = (select max(otherID)
from t2
where id = THE ID FROM THE OUTER QUERY T1
)
I think you see where I'm trying to go with this. I need to reference t1 in the subquery to join it to the max of t2.
I need to know how to create a query like this.
"THE ID FROM THE OUTER QUERY T1" is where my confusion is.
I tried using t1.id, but did not get results.
Try the following
select t1.*, t2.*
from t1
join t2 on t1.id = t2.id
join (select id, max(otherID) as max_otherID
from t2
group by id
) a ON a.id = t1.id and a.max_otherID = t1.otherID
Using a sub-query on the join often gives better performance than using it in the where clause.