I have a problem joining two tables:
table1
id name
1 aaa
2 bbb
3 ccc
table2
id table1_id name
1 1 x1
2 1 x2
3 2 s1
table1 is the main table, table2 contains attributes.
I need to join and search both tables, but display distinct results from first table.
When using JOIN I get multiple results from table2.
The scenario is I need to search main table TABLE1 and ALL ATTRIBUTES in TABLE2 and return if found
select distinct(name) from table1 inner join table2 on table1.id = table2.table1_id where table2.name = x2;
Should do the trick.
If you need entries which exists in both tables:
SELECT * from Table1 t1
WHERE YourConditionsHere
AND EXISTS (SELECT 1 from Table2 t2
WHERE t1.Id = t2.Table1_id
AND YourConditionsHere)
if you need entries from Table1 for which does not exists enteries in Table2
SELECT * from Table1 t1
LEFT JOIN
(SELECT * from Table2
WHERE YourConditionsHere
) t2
ON (t1.Id = t2.Table1_id)
WHERE YourConditionsHereForTable1
another option
select * from table1 t1 where t1.id in (select table1_id from table2 t2 where t2.name = "x1");
it's probably best to check query plains (i.e. EXPLAIN) for all suggested queries and check the one that performs best for your exact scenario.
Related
there is 2 tables
table1
ID
1
2
4
6
7
TABLE2
2
4
6
i want those number from table1 which is not in table2 how i do this ?
i try this
select id from table1 t1
inner join table2 t2 on t1.id=t2.id
where t1.id not in (select id from table2)
but this is not working
SELECT t1.id
FROM table1 t1
LEFT JOIN table2 t2 ON t2.id = t1.id
WHERE t2.id IS NULL
Conceptually, we select all rows from table1 and for each row we attempt to find a row in table2 with the same value for the id column. If there is no such row, we just leave the table2 portion of our result empty for that row. Then we constrain our selection by picking only those rows in the result where the matching row does not exist. Finally, We ignore all fields from our result except for the id column (the one we are sure that exists, from table1).
try this:
select id from table1 t1 where t1.id not in (select t2.id from table2 t2)
You don't need to join the two tables in this case. You could just do
select id from table1 A where A.id not in (select B.id from table2 B);
You could also just simply use the sql set difference EXCEPT operator to achieve this
(select id from table1) except (select id from table2);
Use NOT IN or NOT EXISTS
select id from table1 t1
where t1.id not in (select id from table2)
select id from table1 t1
where not exists (select id from table2 where id = t1.id)
This is my many-to-many table:
Table3:
ID_TABLE3
ID_TABLE1_FK
ID_TABLE2_FK
Some_Field
Now what I want is to do a select of all records from TABLE2 where ID_TABLE1_FK in TABLE3 = 3. This is my query, and It returns all records, but It adds all fields of TABLE3 at end - WHICH IS NOT DESIRED !! :
SELECT * from TABLE2
JOIN TABLE3 ON TABLE3.ID_TABLE2_FK = TABLE2.ID_TABLE2
WHERE TABLE3.ID_TABLE1_FK= 3
So where am I wrong ?
Just use a regular JOIN and select the columns you really want;
SELECT t2.*
FROM TABLE2 t2 JOIN
TABLE3 t3
ON t3.ID_TABLE2_FK = t2.ID_TABLE2
WHERE t3.ID_TABLE1_FK = 3;
This could conceivably produce duplicates (if they are in TABLE3). So, you might be better off with:
SELECT t2.*
FROM TABLE2 t2
WHERE EXISTS (SELECT 1
FROM TABLE3 t3
WHERE t3.ID_TABLE2_FK = t2.ID_TABLE2 AND t3.ID_TABLE1_FK = 3
);
My query is:
SELECT *
FROM table1
RIGHT JOIN table2 on table1.ID = any(table2.parents)
WHERE table1.ID = 1
My first table is:
ID | desc
123 | Data123
231 | Data231
My second table is:
ID | parents
1 | {123,231}
2 | {123}
But this query isn't working. I am trying to get the data from both 123 and 231, how do I fix this?
any(table1.parents)
parents doesn't exists in table1.
Try to change places
SELECT *
FROM table1
RIGHT JOIN table2 on table1.ID = any(table2.parents)
WHERE table2.ID = 1
You didn't specify what exactly you want, but if you just want to find rows in table1 where the IDs are present in table2.parents, the following should do it:
select t1.*
from table1 t1
where exists (select *
from table2 t2
where t1.id = any(t2.parents))
order by t1.id;
If you want information from table2 as well you need a join (and I don't think you want an outer join):
select *
from table1 t1
join table2 t2 on t1.id = any(t2.parents)
order by t1.id
Due to the nature of a join that would return the row (123,Data123) twice - don't know if you want that or not.
Example: http://rextester.com/PUOL76353
I have 2 tables with the same structure (field names). Table1 and Table2.
I need to return all records from Table1 and only records from Table2 that do not match/join to a record in Table1.
Table2 has more records than Table1.
I am joining the 2 tables on 3 fields.
So basically I want all records from table1 returned and only records that don't have a match (joining on the 3 fields) to table1 from table2 returned.
Put another way, Table1 records take precedence over table2 records in my final result output when the records exist in both tables (same value for the 3 fields)
I started writing something like the below but I don't think it will work. Should I use a left outer join instead?
Select * from table1 t1
left join table2 t2 on t1.id = t2.id and t1.date = t2.date and t1.custid= t2.custid
where t2.id is null or t2.date is null or t2.custid is null
So, you need every row from table1 plus the rows from table2 that don't match with table1?:
SELECT *
FROM table1
UNION ALL
SELECT *
FROM table2 t2
WHERE NOT EXISTS(SELECT * FROM table1
WHERE id = t2.id
AND date = t2.date
AND custid = t2.custid);
Select * from table1 t1
Union
Select * from table2 t2
Where Not exists
(Select * from table1
Where id = t1.id
and date = t1.date
and custid= t1.custid)
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 )