I'm looking to get information from one table, use that to then get data from a 2nd table and then reference the data from the 2nd table to get all relevant fields. i.e:
Table1:
ID
--
69
Table2:
entity_id | id
----------------
69 | 134
Table3:
id | postcode | cost
----------------------
134 | m21 6fh | 850
I need to do this for each entry in table1. I have been trying to use the LEFT JOIN which works until I hit the third table.
Does this not work?
SELECT *
FROM table1
LEFT JOIN table2 ON table1.ID = table2.entity_id
LEFT JOIN table3 ON table2.ID = table3.ID
Note: you will only get table3 data if you have table2 data, which is unavoidable.
Try this:
SELECT t1.*, t2.*, t3.* FROM Table1 t1
LEFT JOIN Table2 t2 ON t2.entity_id = t1.id
LEFT JOIN table3 t3 ON t3.id = t2.id
Try following
Select t1.*, t2.*, t3.* from table1
left join table2 on t1.id = t2.id
left join table3 on t1.id = t3.id -- change to t2.id = t3.id if you want to fetch only when id exists in table2
Note, result will alter if you will use inner join at any place, or use t2.id = t3.id instead of t1.id = t3.id to join on third table.
Try simply in this way:
SELECT Table3.* FROM Table1, Table2, Table3
WHERE table1.ID = table2.EntityId
AND table3.id = table2.id
Related
How can I do something like select * from T1 inner join T2 on (T1.ID=T2.ID OR T1.ID2=T2.ID)
When I execute this code, it seems to fall in a infinity loop so I guess I'm wrong.
In other words, how can I match one of two columns from T1 to one column from T2
T1
ID ID2
1 10
2 20
T2
ID value
1 dummy10
20 dummy20
Result
ID ID2 value
1 10 dummy10
2 20 dummy20
Try to do like this:
select *
from T1, T2
where T1.ID = T2.ID or T1.ID2 = T2.ID
you can use 2 select statements with union, like this:
select
t1.ID,
t1.ID2,
t2.value
from Table1 as t1
inner join Table2 as t2 on t1.ID = t2.ID
UNION
select
t1.ID,
t1.ID2,
t2.value
from Table1 as t1
inner join Table2 as t2 on t1.ID2 = t2.ID
/* this will exclude values selected by other statement */
where t1.ID2 not in (select ID2 from Table1 inner join Table2 on Table1.ID = Table2.ID)
The only issue I can see with the code you provide is that you have not specified from which table you want the common column ID to be selected:
proc sql;
select
t1.*
,t2.value
from t1
inner join t2
on t1.id = t2.id or t1.id2 = t2.id;
quit;
Otherwise, your code should work. Perhaps the size of the data being joined is the problem?
I'm looking to do what I believe is a double-nested check across three tables, but have no idea how to do so.
I have Table1, Table2, and Table3.
All are tied by an ID and a "Longform" and "Shortform" in Table1:
I'm trying to find:
Entries whose IDs appear in Table2 that have the same Longform as those in Table3, but don't share the same Shortform.
This is about as far as I've gotten:
SELECT T2.Longform,T2.Shortform FROM(
SELECT Table1.Longform,Table1.Shortform,Table1.ID FROM OuterTable1.Table1
LEFT JOIN OuterTable2.Table2 on Table1.ID = Table2.ID)
WHERE Table2.ID IS NOT NULL) T2
;
I know I'm probably going to have to do another nested select, or a join, on Outertable3.Table3 but I'm not sure which... Or where...
Any help appreciated as always.
Try the following:
Select *
(
Select T1.*
from T2
inner join T1
on T1.ID = T2.ID
) as Tab
inner join
(
Select T1.*
from T3
inner join T1
on T1.ID = T3.ID
) as Tab2
on Tab.id = Tab2.id
and Tab.Longform = Tab2.Longform
and Tab.Shortform <> Tab2.Shortform
To get the longform join table1 to table2 or table3. Then use EXISTS to check in a subquery if the IDs of table1 are different but the longform is equal.
SELECT *
FROM table2 t21
INNER JOIN table1 t11
ON t11.id = t21.id
WHERE EXISTS (SELECT *
FROM table3 t32
INNER JOIN table1 t12
ON t12.id = t32.id
WHERE t12.id <> t11.id
AND t12.longform = t11.longform);
Assuming ID is unique in all three tables
Select t2.id,t2.shortform, t1.shortform AS shortformTab1, t2.longform
FROM table2 t2
JOIN table3 t3
ON t2.id = t3.id AND t2.longform = t3.longform
JOIN table1 t1
ON t2.id = t1.id AND t2.shortform != t1.shortform
I have a table Table1. My application code reads from Table1 like this:
Select id, table2_id, table3_id from Table1
I would like it to also return values name from tables Table2 and Table3 by changing my query like this:
select t1.id, t1.table2_id, t1.table3_id, t2.name, t3.name
from table1 t1
left outer join table2 t2 on t1.table2_id = t2.id
left outer join table3 t3 on t1.table3_id = t3.id
However, I don't want to change the behavior of the original query, which returns 1 result per row in Table1.
I believe my changes to the query are safe because they t2.id and t3.id are unique columns, so Table2 and Table3 will contain at most 1 record for each Table3 record. If I was to user inner join, this changes would not be safe, because my query would return no results if Table2 or Table3 happen to not contain the expected record.
For this scenario, are my changes safe and correct? Or is it necessary to write some subqueries to join on?
Your query looks safe:
select t1.id, t1.table2_id, t1.table3_id, t2.name, t3.name
from table1 t1 left join
table2 t2
on t1.table2_id = t2.id left join
table3 t3
on t1.table3_id = t3.id;
You can also phrase this using correlated subqueries (or a lateral join):
select t1.*,
(select t2.name from table2 t2 where t1.table2_id = t2.id) as t2_name,
(select t2.name from table3 t3 where t1.table2_id = t3.id) as t3_name,
from table1 t1;
This is even more of a guarantee that there are no duplicates. If there were, the query would return an error.
I have some set of records, but now i have to select only those records from this set which have theeir Id in either of the two tables.
Suppose I have table1 which contains
Id Name
----------
1 Name1
2 Name2
Now I need to select only those records from table one
which have either their id in table2 or in table3
I was trying to apply or operator witin inner join like:
select *
from table1
inner join table2 on table2.id = table1.id or
inner join table3 on table3.id = table1.id.
Is it possible? What is the best method to approach this? Actually I am also not able to use
if exist(select 1 from table2 where id=table1.id) then select from table1
Could someone help me to get over this?
Use left join and then check if at least one of the joins has found a relation
select t1.*
from table1 t1
left join table2 t2 on t2.id = t1.id
left join table3 t3 on t3.id = t1.id
where t2.id is not null
or t3.is is not null
I would be inclined to use exists:
select t1.*
from table1 t1
where exists (select 1 from table2 t2 where t2.id = t1.id) or
exists (select 1 from table3 t3 where t3.id = t1.id) ;
The advantage to using exists (or in) over a join involves duplicate rows. If table2 or table3 have multiple rows for a given id, then a version using join will produce multiple rows in the result set.
I think the most efficient way is to use UNION on table2 and table3 and join to it :
SELECT t1.*
FROM table1 t1
INNER JOIN(SELECT id FROM Table2
UNION
SELECT id FROM Table3) s
ON(t.id = s.id)
Alternatively, you can use below SQL as well:
SELECT *
FROM dbo.Table1
WHERE id Table1.IN ( SELECT table2.id
FROM dbo.table2 )
OR Table1.id IN ( SELECT table3.id
FROM Table3 )
I got
table1 table2 table3
id id id
name table1id customerid
table3id
How can i fetch the table1.name joining table2 where customerid = someid and table3id not exist in table2
SELECT
t1.id
t1.name
FROM
Table1 t1
LEFT JOIN Table2 t2
on t1.id = t2.table1id
LEFT JOIN Table3 t3
on t2.table3id = t3.id
AND t3.customerid = 93
WHERE
t3.id IS NULL
SELECT table1.name
INNER JOIN table2 ON table1.id = table2.table1id
WHERE table2.id NOT IN (SELECT id FROM table3)