I have the following tables
Table A
ID "Other Columns"
1
2
3
Table B
ID "Other Columns"
3
4
5
What is the efficient way to return the below result?
Result
ID "Other Columns"
1
2
4
5
A full outer join should work, and only go through each table once. They can be tricky, so test carefully!
SELECT
isnull(A.ID, B.ID) ID
,"Other columns" -- Handle nulls properly!
from TableA A
full outer joing TableB B
on B.ID = A.ID
where not (A.ID is not null
and B.ID is not null)
You want to use left and right join and union them
Select TableA.ID as 'ID','Other Colums'
FROM TableA Left join TableB
ON TableA.ID=TableB.ID
WHERE TableB.ID IS NULL
UNION
Select TableB.ID as 'ID','Other Colums'
FROM TableA Right join TableB
ON TableA.ID=TableB.ID
WHERE TableA.ID IS NULL
You can try like this
SELECT
COALESCE(a.id, b.id),
OtherColumns
FROM #tablea a
FULL JOIN #tableb b
ON a.id = b.id
WHERE a.id IS NULL
OR b.id IS NULL
You can do this with a UNION ALL using a LEFT JOIN to determine if the ID is not in the other table. Keep in mind that the column count and datatypes between the two tables must match up:
Select A.Id, A.OtherColumns
From TableA A
Left Join TableB B On A.Id = B.Id
Where B.Id Is Null
Union All
Select B.Id, B.OtherColumns
From TableB B
Left Join TableA A On A.Id = B.Id
Where A.Id Is Null
Not quite sure what you need with the "Other columns", but you could use EXCEPT:
Select ID from TableA
EXCEPT
Select ID from TableB
If you need Other columns from TableA you could use:
Select ID, OtherColumn1, OtherColumn2 from TableA
where ID not in (select ID from TableB)
(as long as ID cannot be null in TableB)
I broke down each part to be clearer!
select *
into #temp
from
TabA Full outer join TabB
on TabA.ColNameA = TabB.ColNameB
select *
into #temp2
from #temp
where (ColNameA is Null Or ColNameB is null)
select ColNameA from #temp2
where ColNameA Is not null
union
select ColNameB from #temp2
where ColNameB Is not null
Related
I have two tables and I want to select all values from "TABLE A" that have a different value in a column from "TABLE B".
I tried this
SELECT A.* FROM tableA A
left join tableB B ON A.id = B.id WHERE B.column <> 1;
But this just return the value that I want to ignore.
SELECT A.*
FROM tableA A
INNER JOIN tableB B
ON A.id = B.id
WHERE B.column != 1;
or
SELECT A.* FROM tableA A WHERE A.Id NOT IN (SELECT B.Id FROM tableB B WHERE B.column != 1)
Depends on your SQL you can use <> or !=
I would suggest not exists:
SELECT A.*
FROM tableA A
WHERE NOT EXISTS (SELECT 1 FROM tableB B WHERE A.id = B.id AND B.column = 1);
Using a JOIN can result in duplicated rows, if more than one row in B matches the JOIN condition.
I need make a decision which table should be use in join statement depend on values in another table
I tried using CASE and COALESCE but can't achieve any success.
TableA has A and B and C and many other columns
TableB has ID and NAME columns
TableC has ID and NAME columns
My select statement is;
Select A.D, A.E, A.F From TableA A
If A.E = 1 then the following join should be used
left outer join TableB B ON A.B = B.ID
and B.NAME should be returned in the select statement
If A.E = 2 then the following join should be used
left outer join TableC C ON A.B = C.ID
and C.NAME should be returned in the select statement
Just add your conditions to the joins, and then use a case statement to pull the correct field to your result set e.g.
select A.D, A.E, A.F
, case when B.[Name] is not null then B.[Name] else C.[Name] end [Name]
from TableA A
left outer join TableB B ON A.B = B.ID and A.E = 1
left outer join TableC C ON A.B = C.ID and A.E = 2
Join tablea with the union of tableb with an extra column with value 1 and tablec with an extra column with value 2 and apply the conditions in the ON clause:
select
a.D, a.E, a.F, u.NAME
from tablea a
left join (
select *, 1 col from tableb
union all
select *, 2 col from tablec
) u on a.B = u.id and a.E = u.col
I have two tables, tableA which has a list of records and tableB which has restrictions (if any). How can I join the tables that will essentially be an inner join if there are records in tableB or no join if tableB is empty?
ie:
tableA
id | name
1 | val1
2 | val2
tableB (with restrictions)
id | name | userID
1 | val1 | 123
OR tableB (no restrictions)
id | name | userID
is this possible? My attempt below:
SELECT a.*
FROM tableA a
INNER JOIN (CASE WHEN select 1 from tableB = 1 THEN tableB ELSE tableA END) b
ON a.id = b.id
where userID = XXX
EDIT: There is a check on tableB
Just use a left join
SELECT a.*
FROM tableA a
LEFT JOIN tableB b = ON a.id = b.id and b.userid = xxx
I'm not seeing any complexity beyond that at present - given the simplicity of the statement in the original question, I am wondering if you are putting WHERE predicates against the table B - if you are, they need to be in the ON clause of the join
Edited to include your where clause moved.
For empty rows, u can use same query for both restrictions.
I guess you are usign SQL server
Use left join to pull rows if table b is blank
select a.id,a.name
from tableA a left join tableB on a.id = b.id
Demo:
declare #tableA table (id int, name varchar(10))
insert into #tableA
select 1, 'name'
union all
select 2,'name1'
union all
select 3,'name2'
declare #tableb table (id int, name varchar(10))
select a.id,a.name
from #tableA a left join #tableb b on a.id = b.id
this will pull all records from tableA if tableB is empty and only matching records if it is not:
select a.id, a.name
from tableA a
join tableB on a.id = b.id
where exists (select 1 from tableB)
union all
select a.id, a.name
from tableA a
where not exists (select 1 from tableB)
I have a table A and B with a common ID field. I would like to do a full outer join on these tables, selecting the ID and either 'table A' or 'table B', depending on which table the ID came from.
SELECT ID, ['tableA'|'tableB']
FROM A FULL OUTER JOIN B ON A.ID = B.ID
WHERE A.ID IS NULL OR B.ID IS NULL
Try this:
SELECT COALESCE(A.ID , B.ID) AS ID ,
CASE WHEN A.ID IS NOT NULL AND B.ID IS NULL THEN <tableA results>
WHEN A.ID IS NULL AND B.ID IS NOT NULL THEN <tableB results>
END AS results
FROM A FULL OUTER JOIN B ON A.ID = B.ID
WHERE A.ID IS NULL OR B.ID IS NULL
So this is what I came up with after a little help from Tab.
SELECT ID, SELECT CASE WHEN ID IN (SELECT ID FROM A) THEN 'tableA'
WHEN ID IN (SELECT ID FROM B) THEN 'tableB'
FROM A FULL OUTER JOIN B ON A.ID = B.ID
WHERE A.ID IS NULL OR B.ID IS NULL
I have two table a and b
table a
ID
a
b
c
table b
ID Value
a 1
b 2
default 0
So I want to join two tables on ID when exactly matching, otherwise use default value
The desired results
ID Value
a 1
b 2
c 0
Use a LEFT OUTER JOIN for that purpose like
select t1.ID, COALESCE(t2.Value, 0) as Value
from tablea t1
left join tableb t2 on t1.ID = t2.ID;
Try this:
SELECT a.ID, b.Value
FROM a
INNER JOIN b
ON a.ID = b.ID
UNION ALL
SELECT a.ID, b.Value
FROM a
CROSS JOIN b
WHERE
a.id <> b.id
This will provide you with all matching IDs, then the UNION of the CROSS JOIN query should provide the default value for non-matching IDs.
Try this:
SELECT t1.ID,
COALESCE(t2.Value, (SELECT Value FROM tableb t3 WHERE ID ='default')) AS Value
FROM tablea t1
LEFT JOIN tableb t2 on t1.ID = t2.ID;