I could not find a solution for this. Maybe also because it is a bit difficult to explain.
I got table1 with key1.
I got table2 with key2, value1.
My Statement:
Select * From table1 As t1
Left Join table2 As t2 On t2.key2 = t1.key1
Where t2.value1 Is Null Or t2.value1 > 123;
Now I have some key1 in table1, but not the corresponding key2 in table2. Because of that I do not have those keys in my result, but I need them in it. If the key in not in table2, then value1 sadly is not null. Is there some 'value' I can check there?
Normally, the condition on the left join would go in the on clause.
I suspect you want:
Select *
From table1 t1 Left Join
table2 t2
On t2.key2 = t1.key1 and t2.value1 > 123;
This will return all rows from t1 along with matching rows -- if any -- from table2.
Your version will return all rows from table1 where there is either a matching row with value1 > 123 or no matching rows at all. In other words, it will filter out rows from table1 where all values in table2 are <= 123. This is only useful on very rare occasions.
Try the below query and check
Select * From table1 As t1 INNER JOIN table2 As t2 On t2.key2 = t1.key1 Where t2.value1 Is NULL Or t2.value1 > 123;
It should work for your logic
Related
I have two tables and have mentioned the layout of tables in the below screenshot.
Using Id column I need to join two tables. Whenever there is a match with Id (example Id is a2), I need to take the corresponding values from Table2. In some scenario, Id from Table1 will not be there in Table2 (example Id is a1). In that case, I have to take values from Table2 where the value of Id in Table2 is all.
For better clarification, I have mentioned the Expected output in the below screenshot.
I tried the below code, but don't seem to be working.
select distinct t1.Id,t1.Name,t2.Phone1,t2.Phone2
from Table1 t1
left join Table1 t2 on t1.Id = case when t2.Id is null then t1.Id else t2.Id end
Any help is greatly appreciated.
You can use two left joins, where the second brings in the default values:
select t1.*, coalesce(t2.phone1, t2d.phone1) as phone1, coalesce(t2.phone2, t2d.phone2) as phone2
from table1 t1 left join
table2 t2
on t1.id = t2.id left join
table2 t2d
on t2d.id = 'All' and t2.id is null;
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 have a SQL Insert statement that needs to insert records into another table only if the the record doesn't exist in table2 or the zip code has changes in table1. I have tried the following but it throws an error and it is the logic I am looking for:
INSERT INTO table2
SELECT id, zip
FROM table1 t1
JOIN table2 t2
ON t1.id = t2.id and t1.zip <> t2.zip
I also need it to insert the records if the id doesn't exist at all in table2. I have googled the crap out of this and can't seem to find the solution anywhere.
What about this?
INSERT INTO table2
SELECT t2.id, t2.zip
FROM table1 t1
LEFT OUTER JOIN table2 t2
ON t1.id = t2.id
WHERE (t1.id IS NULL OR t2.zip <> t1.zip)
Also, be sure to clarify which table's id and zip columns you are asking for.
You should always include column lists when doing inserts. Second, your query doesn't quite capture your logic. You need a left outer join to find the records that don't exist in the second table. Perhaps this might do what you want:
INSERT INTO table2(id, zip)
SELECT id, zip
FROM table1 t1 LEFT JOIN
table2 t2
ON t1.id = t2.id
WHERE (t1.zip <> t2.zip) or (t2.zip is null)
You just need a WHERE NOT EXISTS clause
INSERT INTO table2
SELECT id, zip
FROM table1
WHERE NOT EXISTS (SELECT 1 FROM table2 WHERE table2.id = table1.id AND table2.zip = table1.zip)
Is there a quicker way to get the ids that exist in table1 but not exist in table2 and insert them in table2?
insert into table2 (id)
select id
from table1
where table1.id not in (select id from table2)
In addition to your solution using the in operator try the exists one
select id
from table1 t1
where not exists (
select 1
from table2
where id = t1.id
)
If the subquery returns an empty set not exists evaluates to true
The outer join
select id
from
table1 t1
left join
table2 t2 on t1.id = t2.id
where t2.id is null
Use explain analyze to compare
there are two tables ...know i need
1st condition:
all the records in table
2 nd condition:
In table2 i need only records which have data
...i want one query for the aove two conditions...
SELECT
*
FROM Table1 t1
INNER JOIN Table2 t2 on t1.PK = t2.FK
This will return all rows in table1 that have at least one corresponding row in table2
But if you want all rows from t1 no matter what then this may be what you want
SELECT
*
FROM Table1 t1
LEFT JOIN Table2 t2 on t1.PK = t2.FK
Finally, As I dont know the structure in place perhaps table1 and table2 have similar structures. If this is true perhaps you may want a union of the two
SELECT
*
FROM Table1 t1
UNION ALL
SELECT
*
FROM Table2 t2