I want to delete an entry in a table where multiple fields match the results of another select subquery which takes data from another table.
query :
DELETE FROM table1
WHERE carriedby_circuit IN (SELECT
circuit_id
FROM table2
WHERE circuit_name IN (SELECT
t.sc_prod_service_id
FROM table3 t));
So I want to modify the query in such a way that if circuit_id form table2 is present in carriedBY_circuit or in CARRIED_CIRCUIT columns of table1. it should delete the row from table1.
You can try with merge:
merge into table1 t1
using (select t2.circuit_id from table2 t2 inner join table3 t3 on t2.circuit_name = t3.sc_prod_service_id) d
on (d.circuit_id = t1.carriedby_circuit or d.circuit_id = t1.carried_circuit)
when matched then delete;
Assuming you have 3 tables and you are working with ids. Table1, table2 and table3. Your best approach is to join table2 with table3. Then query its results, to delete from table1.
Example:
DELETE FROM table1
WHERE table1.id IN(SELECT distinct id FROM tabel1 UNION SELECT ID as id FROM tabel2);
PS: The union select will probably duplicate your Id´s, this is why I propose to use distinct.
Related
I have two tables.
Table 1
Id
UpdateId
Name
Table 2
Table1ID
UpdateID
Address
Each time user update, system will insert record to table1. But for table2, system only insert record when there is update in address.
Sample data
Table 1
1,1,name1
1,2,name1
1,3,name1update
1,4,name1update
1,5,name1
1,6,name2
Table 2
1,1,address
1,4,addressupdate
I want to get the result as following
1,1,name1,address
1,2,name1,address
1,3,name1update,address
1,4,name1update,addressupdate
1,5,name1,addressupdate
1,6,name2,addressupdate
How to make use of join condition to achieve as above?
You can use a correlated subquery. Here is standard syntax, but it can be easily adapted to any database:
select t1.*,
(select t2.addressid
from table2 t2
where t2.table1id = t1.id and
t2.updateid <= t1.updateid
order by t2.updateid desc
fetch first 1 row only
) as addressid
from table1 t1;
you can use left join when you want to take all columns from left table t1 even though it doesn't match with the other table with column updateid on t2 table.
select t1.id,t1.updateid,t1.name,t2.address from table1 t1
left join table2 t2
on t2.updateid= t1.updateid
you can read more about joins here
I want to get a value from an IN subquery with two columns, without needing to do two queries.
Sample:
SELECT * FROM table1 WHERE id IN(SELECT id, flags FROM table2);
Now I want to get flags directly. Is it possible, and if yes, how?
Any help is appreciated :)
It sounds like you are trying to achieve one of two things:
1) Select every field of records in table1 (and the associated table 2 flag) where the record's id is also found in the id column of table2. If that is the case, then yes, a join will accomplish what you want:
SELECT t1.*,
t2.flags
FROM table1 t1
JOIN table2 t2
ON t1.id = t2.id;
Note that JOIN is used here (rather than other types of joins such as LEFT JOIN) because JOIN will return only table1 records with a match in table2.id. LEFT JOIN, on the other hand, would return every table1 record, and table1 ids without a match in table2 would simply have null in the flags column of your returned table.
2) Select every field of records in table1 where the record's id is also found in either the id column of table2 or the flags column of table2. If that is the case, there are a few ways you could get the desired result, but achieving this using a subquery similar to the question
SELECT *
FROM table1
WHERE id IN (SELECT id FROM table2 UNION DISTINCT SELECT flags FROM table2)
You do this using join:
SELECT t1.*, t2.flags
FROM table1 t1 JOIN
table2 t2
ON t1.id = t2.id;
I have two tables where each one contains columns with numbers. I need to compare columns in both tables and extract the number that does exist in first table, and does not exist in second one. I don't need unique value.
I wrote this query:
SELECT Table1.Numbers, Table1.Name
FROM Table1, Table2
WHERE Table1.Numbers != Table2.numbers
Since I am working on several million records can someone recommend more efficient query which would provide me with identical results?
I would use NOT EXISTS:
SELECT Table1.Numbers, Table1.Name
FROM Table1
WHERE NOT EXISTS(
SELECT 1 FROM Table2
WHERE Table1.Numbers=Table2.Numbers
)
Other approaches:
Should I use NOT IN, OUTER APPLY, LEFT OUTER JOIN, EXCEPT, or NOT EXISTS?
You can do this easily by checking for the existance on the number in Table2.
SELECT T1.Numbers
,T1.Name
FROM Table1 T1
WHERE NOT EXISTS (SELECT 1 FROM Table2 T2 WHERE T2.Numbers = T1.Numbers)
Try this (assuming that your Numbers column are not nullable)
SELECT T1.Numbers, T1.Name
FROM Table1 AS T1
LEFT JOIN Table2 AS T2 ON T1.Numbers = T2.Numbers
WHERE T2.Numbers IS NULL;
SELECT
Table1.Numbers, Table1.Name
FROM
Table1, Table2
GROUP BY
Table1, Table2
HAVING
COUNT(*) > 1
I'm working with an access database and I have some tables set up like this.
Table1(Table1Id, Field1, Field2, ...)
Table2(Table2Id, Table1Id, AuditDate, Field1, Field2, ...)
I am trying to select every record in Table1, and those in Table2 with the latest AuditDate. If there is no entry in Table2 to tie back into Table1, I just want to populate a row of what is in Table1 and a bunch of empty fields where the data from Table2 would come from. Here is the query I have so far.
SELECT Table1.TableId,
Table1.Field1,
Table1.Field2,
Table2.Field1,
Table2.Field2
FROM Table1
LEFT OUTER JOIN Table2 ON Table1.TableId = Table2.Table1Id
WHERE Table2.AuditDate = (SELECT MAX(AuditDate) FROM Table2 WHERE Table1.TableId = Table2.Table1Id)
The problem with this is that it only returns two records. There are only two entries in Table2 but I want it to return a row of data for every record in Table1 as well instead of just the ones that find a match in Table2.
The problem is this line:
WHERE Table2.AuditDate = ...
In cases where no Table2 entry exists, AuditDate will be NULL. So you need to test for that:
WHERE Table2.Table2Id IS NULL OR Table2.AuditDate = ...
Guess that if you remove the outer you would get every entry from table 1.
Edit: but if you have more entries in Table 2 than in Table 1 it will still be a problem.
Maybe try a Full JOIN?
I need to write an SQL script that selects one record in table1, then does a lookup in the remaining tables in the database. If it doesn't find the record, I need delete the record from table1. Anyone provide some sample script?
One example
delete table1
where not exists (select 1
from Table2
where table1.SomeColumn = Table2.SomeColumn)
AND table1.SomeColumn = 5 --just an example,
Leave the AND out if you want to delete all the rows from table 1 that do not exist in table 2
you can also use LEFT JOIN or NOT IN
I have done things like this:
DELETE table1
FROM table1
WHERE table1.ID NOT IN (
SELECT RefID FROM Table2
UNION
SELECT RefID FROM Table3
...
)
Assuming RefID are FK's to table1.ID. Is this what you need?
DELETE FROM Table1 WHERE id=10 AND NOT EXISTS (SELECT * FROM Table2 WHERE id=10);
Very generally, (since you gave little details)
Delete Table1 t1
Where [Criteria to find table1 Record]
And Not Exists(Select * From Table2
Where pk = t1.Pk)
And Not Exists(Select * From Table3
Where pk = t1.Pk)
And Not Exists(Select * From Table4
Where pk = t1.Pk)
... etc. for all other tables