I want to update a table based on another table.
I want to update table b using table A. One Id can have multiple serial number in table B. If I want to update all the serial number for a ID then I will pass null in table A, If I want to update only particular serial number then I will pass that serial number. So Serial number is like optional. How to achieve this?
This covers all cases:
SELECT B.ID, B.SerialNumber
FROM TableA A
JOIN TableB B ON A.ID=B.ID AND (A.SerialNumber=B.SerialNumber OR A.SerialNumber IS NULL)
Demo:
WITH TableA AS
(
SELECT * FROM (VALUES
(1,'AB'),
(1,'BC'),
(2,NULL),
(3,'AB')
)T(ID,SerialNumber)
), TableB AS
(
SELECT * FROM (VALUES
(1,'AB'),
(1,'BC'),
(2,'AB'),
(2,'BC'),
(3,'AB'),
(3,'BC'),
(3,'DE')
)T(ID,SerialNumber)
)
SELECT B.ID, B.SerialNumber
FROM TableA A
JOIN TableB B ON A.ID=B.ID AND (A.SerialNumber=B.SerialNumber OR A.SerialNumber IS NULL)
Result
ID SerialNumber
----------- ------------
1 AB
1 BC
2 AB
2 BC
3 AB
You can join both tables :
SELECT [A].[ID]
,[B].[SerialNumber]
,[A].[Values]
FROM [TableA] A
LEFT JOIN [TableB] B ON ([B].[ID] = [A].[ID] AND ([B].[SerialNumber] = [A].[SerialNumber] OR [A].[SerialNumber] IS NULL))
Related
So I'm struggling to find the logic for the next problem:
I got 2 tables
TABLE A has the following column
Postalcode
1111
2222
3333
4444
TABLE B has the following column
Postalcode
1111AA
1111BB
1111CA
2222AA etc
What I would like to have is that if the Postalcodes first 4 numbers are found from Table A in table B, then I would like to have the first result of that postalcode from Table B (4digits+2letters).
e.g. if the postalcode in A is 1111 and substring(postalcode, 1, 4) of Table B is also 1111, then return the first result of that postalcode from Table B --> 1111AA
I can't seem to find the answer for this and I'm struggling for a while now.
Hope you guys have the solution for me.
If for each record in table A you want to match at most one record from Table B, an OUTER APPLY (SELECT TOP 1 ...) should do the trick.
Try:
select a.PostalCode, b1.Postalcode
from table_a a
outer apply (
select top 1 *
from table_b b
where b.Postalcode LIKE a.Postalcode + '%'
order by b.id
) b1
order by a.PostalCode;
If you wish to omit results that have no matching table_b record, change the OUTER APPLY to a CROSS APPLY. A OUTER APPLY is like a LEFT JOIN while a CROSS APPLY is like an INNER JOIN.
See this db<>fiddle fr a demo.
(Credit Bernd Buffen for the data setup. Note that I changed PostalCode from INT to VARCHAR to simplify the match criteria.)
i have change the sample from #Ergest Basha with a virtual column and index
CREATE TABLE table_a (
Postalcode INT ,
KEY idx_sPortalcode (Postalcode)
);
INSERT INTO table_a VALUES
(1111),
(2222),
(3333),
(4444);
CREATE TABLE table_b (
id INT,
Postalcode VARCHAR(25),
sPostalcode INT AS ( 0 + Postalcode) STORED,
KEY idx_sPortalcode (sPostalcode)
);
INSERT INTO table_b (id,Postalcode) VALUES
(1,'1111AA'),
(2,'1111BB'),
(3,'1111CA'),
(4,'2222AA');
SELECT * FROM table_b;
-- EXPLAIN
SELECT b.Postalcode
FROM table_a a
INNER JOIN table_b b ON b.sPostalcode=a.Postalcode
WHERE a.Postalcode=1111
ORDER BY b.id ASC LIMIT 1;
Something like this: MySQL
select b.Postalcode
from table_a a
inner join table_b b on LEFT(b.Postalcode,4)=a.Postalcode
where a.Postalcode=1111
order by b.id asc limit 1;
Check the demo
SQL Server
select top(1) b.Postalcode
from table_a a
inner join table_b b on LEFT(b.Postalcode,4)=a.Postalcode
where a.Postalcode=1111
order by b.id ;
Demo
Edit based on comments*
I think you need something like below, but check #Bernd Buffen suggestion for performance:
WITH cte AS (
SELECT Postalcode, ROW_NUMBER() OVER ( PARTITION BY LEFT(Postalcode,4) ORDER BY id asc ) row_num
FROM table_b
)
SELECT cte.Postalcode
FROM table_a a
INNER JOIN cte on LEFT(cte.Postalcode,4)=a.Postalcode
WHERE row_num = 1 ;
Demo
I have two tables in my database. From the Table B i collect some data. I include by using JOIN the data from Table A. In this table there is a column user_id. The user id in table B is the the id from Table A. No i want to get all data from table A but without showing data if the table A id is in the table B column user_id available. I think the trick is the correct usage of JOIN but i need to check the whole column and not just one line.
SQL Query (which is probably not working)
SELECT * FROM tableB
JOIN tableA
ON tableB.user_id = tableA.id
WHERE tableB.user_id != tableA.id
Please see my example i have prepared in Excel:
To select all the data from tableA where id is not available in tableB you don't need join rather you can use not exists or not in.
I would prefer not exists
Using not exists:
SELECT * from tableA a
WHERE NOT EXISTS (
SELECT 1
FROM tableB b
WHERE b.user_id = a.id
);
using not in:
SELECT * from tableA a
WHERE id not in (SELECT user_id FROM tableB );
DB-Fiddle:
create table TableA (id int, name varchar(50), lastname varchar(50));
insert into TableA values(1,'john','smith');
insert into TableA values(2,'Paul','smith');
create table TableB (id int, user_id int, something varchar(50));
insert into TableB values(1,2,'bla');
insert into TableB values(2,3,'bla');
Query: (using not exists)
SELECT * from tableA a
WHERE NOT EXISTS (
SELECT 1
FROM tableB b
WHERE b.user_id = a.id
);
Output:
id
name
lastname
1
john
smith
Query: (using not in)
SELECT * from tableA
WHERE id not in (SELECT user_id FROM tableB );
Output:
id
name
lastname
1
john
smith
db<fiddle here
I think I get what you want. You want not exists:
SELECT *
FROM tableB b JOIN
tableA a
ON b.user_id = a.id
WHERE NOT EXISTS (SELECT 1
FROM tableA a2
WHERE b.user_id = a2.id
);
EDIT:
I wrote the above, but I didn't fully follow the JOIN conditions. You either seem to want to join on id:
SELECT *
FROM tableB b JOIN
tableA a
ON b.id = a.id
WHERE NOT EXISTS (SELECT 1
FROM tableA a2
WHERE b.user_id = a2.id
);
Or no JOIN at all:
SELECT *
FROM tableB b
WHERE NOT EXISTS (SELECT 1
FROM tableA a2
WHERE b.user_id = a2.id
);
Table A:
id Name
1 a
2 b
3 c
4 d
5 e
Table B:
id Name
3 c
4 d
5 e
Here, id is the primary key connected to Table B.
I need output like this:-
id
1
2
That means, which ids in Table A are not present in Table B
Use EXCEPT operator:
select id from tableA
except
select id from tableB
You can use a left join, which will preserve all records on the left side and associate them with null if no matching record is available on the right side.
This way you can then filter on the right side columns to be null to get the desired outcome
select t1.id
from tableA t1
left join
tableB t2
on t1.id = t2.id
where t2.id is null
Use NOT EXISTS in WHERE clause
SELECT id FROM TableA A
WHERE NOT EXISTS(SELECT 1 FROM TableB B WHERE A.id = B.Id )
Using Not in statement.
Try this:-
Select id from TableA
where id not in (Select id from TableB);
You can use minus:
select * from tableA
minus
select * from tableB
I have two tables
Table A
-------
ID
ProductName
Table B
-------
ID
ProductID
Size
I want to join these two tables
SELECT * FROM
(SELECT * FROM A)
LEFT JOIN
(SELECT * FROM B)
ON A.ID = B.ProductID
This is easy, I will get all rows from A multiplied by rows matched in B, and NULL fields if there is no match.
But here comes the tricky question, how can I get all rows from A with NULL fields for table B, even if there is a match, so I get an extra line with NULL values plus all the matches?
SELECT A.*
, B3.ID
, B3.ProductID
, B3.Size
FROM A
LEFT JOIN
(
SELECT ProductID as MatchID
, ID
, ProductID
, Size
FROM B
UNION ALL
SELECT ID
, null
, null
, null
FROM A A2
) B3
ON A.ID = B3.MatchID
Live example at SQL Fiddle.
Instead of using UNION ALL in a subquery as suggested by others, you could also (and I would) use UNION ALL at the outer level, which keeps the query simpler:
SELECT A.ID, A.ProductName, B.ID, B.Size
FROM A
INNER JOIN B
ON B.ProductID = A.ID
UNION ALL
SELECT A.ID, A.ProductName, NULL, NULL
FROM A
Since every join is going to be successful, we can switch to a full/inner join:
SELECT
*
FROM
A
INNER JOIN
(SELECT ID,ProductID,Size FROM B
UNION ALL
SELECT NULL,ID,NULL FROM A) B
ON
A.ID = B.ProductID
Now would be a very good time to switch to naming columns explicitly, rather than using SELECT *
Or, if, as per #Andomar's comment, you need all of the B columns to be NULL:
SELECT
A.ID,A.ProductName,
B.ID,B.ProductID,B.Size
FROM
A
INNER JOIN
(SELECT ID,ProductID,Size,ProductID as MatchID FROM B
UNION ALL
SELECT NULL,NULL,NULL,ID FROM A) B
ON
A.ID = B.MatchID
I have two tables
Table A:
ID
1
2
3
4
Table B:
ID
1
2
3
I have two requests:
I want to select all rows in table A that table B doesn't have, which in this case is row 4.
I want to delete all rows that table B doesn't have.
I am using SQL Server 2000.
You could use NOT IN:
SELECT A.* FROM A WHERE ID NOT IN(SELECT ID FROM B)
However, meanwhile i prefer NOT EXISTS:
SELECT A.* FROM A WHERE NOT EXISTS(SELECT 1 FROM B WHERE B.ID=A.ID)
There are other options as well, this article explains all advantages and disadvantages very well:
Should I use NOT IN, OUTER APPLY, LEFT OUTER JOIN, EXCEPT, or NOT EXISTS?
For your first question there are at least three common methods to choose from:
NOT EXISTS
NOT IN
LEFT JOIN
The SQL looks like this:
SELECT * FROM TableA WHERE NOT EXISTS (
SELECT NULL
FROM TableB
WHERE TableB.ID = TableA.ID
)
SELECT * FROM TableA WHERE ID NOT IN (
SELECT ID FROM TableB
)
SELECT TableA.* FROM TableA
LEFT JOIN TableB
ON TableA.ID = TableB.ID
WHERE TableB.ID IS NULL
Depending on which database you are using, the performance of each can vary. For SQL Server (not nullable columns):
NOT EXISTS and NOT IN predicates are the best way to search for missing values, as long as both columns in question are NOT NULL.
select ID from A where ID not in (select ID from B);
or
select ID from A except select ID from B;
Your second question:
delete from A where ID not in (select ID from B);
SELECT ID
FROM A
WHERE NOT EXISTS( SELECT 1
FROM B
WHERE B.ID = A.ID
)
This would select 4 in your case
SELECT ID FROM TableA WHERE ID NOT IN (SELECT ID FROM TableB)
This would delete them
DELETE FROM TableA WHERE ID NOT IN (SELECT ID FROM TableB)
SELECT ID
FROM A
WHERE ID NOT IN (
SELECT ID
FROM B);
SELECT ID
FROM A a
WHERE NOT EXISTS (
SELECT 1
FROM B b
WHERE b.ID = a.ID)
SELECT a.ID
FROM A a
LEFT OUTER JOIN B b
ON a.ID = b.ID
WHERE b.ID IS NULL
DELETE
FROM A
WHERE ID NOT IN (
SELECT ID
FROM B)