There are two tables named, for an example A and B.
A and B has a unique column named key_ref. and key_ref is the primary key of both tables
I need to find records in A but not in B. Therefore I wrote a query like,
SELECT a.*,b* from A a,B b WHERE key_ref NOT IN (SELECT key_ref from B)
The issue with this is, I do not get the empty columns of table B for the result. My result should include all the columns of A and B.
If I write my query like following my results get wrong. Is there any way , where I can achieve this even with a join condition.
SELECT a.* from A a WHERE key_ref NOT IN (SELECT key_ref from B)
Please refer following example.
Table A Table B
key ref col1 key ref col2
A aaa A aaa
B bbb B bbb
C ccc C ccc
D ddd
My answer should be,
key ref col1 col2
D ddd
If I understand your request:
You can use a LEFT OUTER JOIN operation so you'll get all rows in A not present in B (with condition in WHERE b.key_ref IS NULL)
Try this:
SELECT *
FROM a
LEFT OUTER JOIN b
ON a.key_ref = b.key_ref
WHERE b.key_ref IS NULL
Is this what you need:
select * from A
except
select * from B
?
If the second table tableB doesn't have a record associated with first table, then how would you display record from second table tableB which are not exists in the first table tableA.
So, the one way is to include NULL as columns ref. to tableB like that :
select a.*, null col2
from tableA a
where not exists (select 1 from tableB b where b.key_ref = a.key_ref);
Related
I have two tables A and B which look like this:
Table A
col1 col2 ID
--------------
a b 1
c d 2
Table B
col3 col4 ID
--------------
x t 1
y u 1
z o 2
m n 2
I want to create this new table:
Table C
col1 col2 col3 col4 ID
-------------------------
a b x t 1
a b y u 1
c d z o 2
c d m n 2
The ID's in A are not the unique ID's of those elements in that list. I just need to add a few more properties from their "parent" table(B) in this new table. I know there will be a lot of repetitions but I don't mind that for now.
I tried this following statement:
INSERT INTO C(SELECT A.*, B.col1, B.col2 from A LEFT OUTER JOIN B ON (B.ID = A.ID));
But it is resulting in something I did not expect. The row count of C must be the same as the row count of B. However when I used this SQL query, the resulting tables row count was even more than the total row count of A and B. I'm a beginner in using SQL I would appreciate any help.
A basic JOIN will do:
select
a.col1,
a.col2,
b.col3,
b.col4,
a.id
from tablea a
join tableb b on a.id = b.id
If I got you right your tables do not have any relation to each other.
So in this case you should be able to do something like this?
Select * from table1, table2
You can also combine this with an insert so you should get your new table
I have two table TableA and TableB. I would like to get a new table value where I want all values of TableA and only one column value from TableB.
Both table has 5 columns where four column names are same, only fifth column name is different. What I want is to get five column values from TableA and insert the fifth column values from TablelB into TableA as sixth Column
I tried with UNION, UNION ALL but didn't get the expected output. I also tried to extraxt fifth column value from TableB and insert into TableA on sixth column but not sure where I did wrong. not getting value as expected
Sample data:
TableA
id name age address entrydatetime
1 AA 20 tyk 2019-05-13:8:35:00
2 AAA 22 tyl 2019-05-13:9:40:00
TableB
id name age address exitdatetime
1 AA 20 tyk 2019-05-13:15:20:00
2 AAA 22 tyl 2019-05-13:16:40:00
Expected output:
NewTable
id name age address entrydatetime exitdatetime
1 AA 20 tyk 2019-05-13:8:35:00 2019-05-13:15:20:00
2 AAA 22 tyl 2019-05-13:8:35:00 2019-05-13:16:40:00
That's as simple as:
SELECT A.*, B.exitdatetime
FROM TableA A
INNER JOIN TableB B ON A.id = B.id;
You need to join the tables when you need to match a table's row to 0-N rows from another table (or maybe even the same table, treated as if it was a different one).
An even better approach would be to name each field you need and not use *. I just used it to make a quick sample.
And just for the record, the database is not normalized, you have data redundancy, which means you can have data inconsistency. For example, if this returns at least one row, you have data inconsistency:
SELECT *
FROM TableA A
INNER JOIN TableB B ON A.id = B.id
WHERE A.name != B.name OR A.age != B.age OR A.address != B.address;
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 designed below query for my delete operation. I am new to SQL and just wanted to check with experienced people here if it is fine or any better way to do this. I am using DB2 database
DELETE FROM TableD
WHERE B_id IN
(
SELECT B.B_id
FROM TableB tB
INNER JOIN TableA tA
ON tB.A_id = tA.A_id
WHERE A_id = 123
) AND
C_id IN (1,2,3)
This has two IN clause which I am little worried and not sure if I could use EXISTS clause anywhere.
Database Structure as below:
Table A has ONE TO MANY relation with Table B
Table B has ONE TO MANY relation with Table C
Table B has ONE TO MANY relation with Table D
Table D has composite primary key ( B_id, C_id )
Table D data somewhat similar to below
B_id|C_id
----------
1 | 1
1 | 2
1 | 3
2 | 4
2 | 5
3 | 5
Here I have to delete rows which have C_id in array of values. But since the index is a composite of B_id and D_id, I am retrieving related B_id to the particular entity of Table A by equality operator A_id=123
There isn't necessarily anything wrong with your method. However, a useful alternative technique to know is merge:
merge into TableD
using (
select distinct
B.B_id
from TableB tB
inner join TableA tA on
tB.A_id = tA.A_id and
A_id = 123
) AB
on
TableD.B_id = AB.B_id and
C_id in (1,2,3)
when matched then delete;
Note that I had to use distinct on the inner query to prevent duplicate matches.
You can use merge like this too :
merge into TableD
using TableB tB
on B.B_id = TableD.B_id
and tB.A_id in (select A_id from TableA tA where A_id = 123)
and C_id in (1,2,3)
when matched then delete;
DELETE FROM TableD tD
WHERE
EXISTS (
SELECT
tB.B_id
FROM
TableB tB
WHERE
A_id = 123
AND tB.B_id = tD.B_id
)
AND C_id IN (1, 2, 3)
I am trying to do a multi query but I don't want to use sub queries i.e:
SELECT column1
FROM table1
WHERE
EXISTS (SELECT column1 FROM table2 WHERE table1.column1 = table2.column1);)
I thought of using a JOIN but so far my best result was this:
SELECT *
FROM table1
JOIN table2 ON table1.t1id = table2.t2id
WHERE table1.id = 5;
This would be good except of the fact that I get a duplicate column (the id in table 1 and 2 are foreign keys).
How do I remove the duplicate column if possible?
UPDATE:
Table1:
tableA_ID, TABLEB_ID
1, 1
1, 4
3, 2
4, 3
TableA: ID, COL1, COL2
1, A, B
2, A, B
3, A, B
4, A, B
TableB: ID, Col3, COL4
1, C, D
2, C, D
3, C, D
4, C, D
I want to get all or some of the columns from TableA according to a condition
Sample: Lets say the condition is that tableA_ID = 1 which will result in the 2 first rows in the table then I want to get all or some of the columns in TableA that respond to the ID that I got from Table1.
Sample: The result from before was [{1,1}{1,4}] which means I want from TableA the results:
TableA.ID, TableA.COL1, TableA.COL2
1,A,B
4,A,B
The actual results I get is:
Table1.tableA_ID, Table1.TABLEB_ID, TableA.ID, TableA.COL1, TableA.COL2
1,1,1,A,B
1,4,4,A,B
Is this what you're looking for?
select a.id, a.column1, b.column2
from table1 a
left join table2 b on a.id = b.otherid;
You can't change the column list of a query based on the values it returns. It just isn't the way that SQL is designed to operate. At best, you can return all of the columns from the second table and ignore the ones that aren't relevant based on other values in that row.
I'm not even sure how a variable column list would work. In your scenario, you're looking for two discrete values separately. But that's not the only scenario: what if the condition is tableA_ID in (1,2). Would you want different numbers of columns in different rows as part of a single result set?
Getting just the columns you want (just from specific tables, as you say) is the easy part (btw -- don't use '*' if you can help it -- topic for another discussion):
SELECT
A.ID,
A.COL1,
A.COL2
FROM
TABLE1 Bridge
LEFT JOIN TABLEA A
ON Bridge.TABLEA_ID = A.ID
LEFT JOIN TABLEB B
ON Bridge.TABLEB_ID = B.ID
Getting the rows you want will be the harder part (influenced by your choice of joins, among several other things).
I think you'll need to select only the fields of table A and use a distinct clause. Rest of your query will remain as it is. i.e.
SELECT distinct table1.*
FROM table1
JOIN table2 ON table1.t1id = table2.t2id
WHERE table1.id = 5;