Lets say there are three table T1,T2 and T3. The values in T2 and T3 are linked with T1. I want to fetch records that are present in T1 but not in T2 marked as '1', records that are present in T1 but not in T3 as 2, and if record is present in T1 but not present in T2 and T3 , then marked as '3'.
Following example can help:
Select T1.ID,
CASE WHEN T2.ID IS NULL THEN 1 END AS T1T2,
CASE WHEN T3.ID IS NULL THEN 2 END AS T1T3,
CASE WHEN T2.ID IS NULL AND T3.ID IS NULL THEN 3 END AS T1T2T3
From T1 LEFT JOIN T2
ON T1.ID = T2.ID
LEFT JOIN T3
ON T1.ID = T3.ID;
Cheers!!
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?
After conducting a left join, I was left with many null (empty) values. How may I replace those null values with a 0 in only certain columns within the same query?
select
m1.*, t2.Apple, t3.Berry, t4.Cherry
from
table1 as t1
left join table2 as t2 on t1.id = t2.id
left join table3 as t3 on t1.id = t3.id
left join table3 as t4 on t1.id = t4.id
;
Example Output
ID Apple Berry Cheery
1 1 NULL 1
2 1 NULL NULL
3 NULL 1 NULL
4 NULL NULL NULL
You can use coalesce() to replace null values with 0s:
select
t1.*,
coalesce(t2.Apple, 0) as apple,
coalesce(t3.Berry, 0) as berry,
coalesce(t4.Cherry, 0) as cherry
from
table1 as t1
left join table2 as t2 on t1.id = t2.id
left join table3 as t3 on t1.id = t3.id
left join table4 as t4 on t1.id = t4.id
;
Note that this assumes that all 3 fruit columns are of a numeric datatype.
Side note: I fixed a few typos on table aliases in your original query.
I have two tables t1 & t2. In t1, there are 1641787 records. In t2, there are 33176007 records. I want to take two columns from table2 and keep everything of t1. When I use left join with t1 to t2, I got more records than t1. I would like to get a similar number of records as t1 after joining. Please give me a suggestion. Here is my code:
SELECT t1.*,
t2.City
FROM t1
LEFT JOIN
t2
ON t1.ID = t2.ID;
You can aggregate and choose an arbitrary value:
select t1.*, t2.city
from t1 left join
(select t2.id, any_value(t2.city) as city
from t2
group by t2.id
) t2
on t1.id = t2.id;
In T1 I have a 50 ID'ss. I'm trying to find which ones are in T2. And add row name "test" next to ID with info about occurrence in T2. But when I put my code I receive only ID's which are included in T2. What I`m doing wrong?
SELECT DISTINCT t1.id, CASE WHEN t1.id IS NULL THEN 0 ELSE 1 END AS test
FROM t2
JOIN t1 ON t2.id = t1.id
You can use outer join:
SELECT DISTINCT t1.id, CASE WHEN t2.id IS NULL THEN 0 ELSE 1 END AS test
FROM t1 LEFT JOIN t2 ON t2.id = t1.id
Use exists:
select t1.*,
(case when exists (select 1 from t2 where t2.id = t1.id) then 1 else 0 end) as flag
from t1;
Note that select distinct is not needed. That construct just slows down queries, if it is not needed.
Use Left Join to get the unmatched rows as well.
select t1.id
, case when t2.id is null then 0 else 1 end as test
from t1
left outer join t2
on t1.id = t2.id
Let's say I have a table t1 with only one column: id, and I have a table t2 with two columns: id and Memo. I need to select those id from t1, for which there is NO row in t2 that satisfies both of the following two conditions t1.id = t2.id and t2.Memo = 'myText'. How can I do that? I have tried using join, but that selects row that do satisfy some conditions, whereas I need the opposite.
SELECT *
FROM t1
WHERE NOT EXISTS (SELECT 1
FROM t2
WHERE t2.id = t1.id
AND t2.Memo = 'myText')
One way to do it is using LEFT JOIN:
select id
from t1
left join t2
on t1.id = t2.id and t2.Memo = 'myText'
where t2.id is null
I'm not good in understanding your question:
You mean those t1.id EXISTS in t2 BUT the corresponding t2.Memo <> 'myText'?
SELECT t1.id FROM t1 JOIN t2
ON t1.id = t2.id
HAVING t1.id NOT IN (SELECT id FROM t2 WHERE Memo = 'myText');
Or all t1.id either NOT EXISTS in t2 or EXISTS but Memo <> 'myText'?
SELECT id FROM t1 WHERE id NOT IN (SELECT id FROM t2 WHERE Memo = 'myText');