SO I've searched high and low, trying other tips used on this forum to no avail.
So trying to delete using inner join in Oracle SQL Developer (v3.2.20.09)
Table I wish to delete from (Table1, column name Column1), where the data matches the column 'Column2' in 'Table2.
I know there are some differences between Oracle/Microsoft SQL, tried multiple queries such as below, with slight variation (using open/close brackets, inner joins, WHERE EXISTS, WHERE (select's).
TRY:
delete from table2 where
exists (select column1 from table1);
delete from table2,
inner join table1 on table2.column2 = table1.column1;
What are the problem(s) of the code that I wrote?
The EXISTS version would look like this:
delete from table2
where exists (select *
from table1
where table1.column1 = table2.column2);
Alternatively you can use an IN clause
delete from table2
where column2 in (select column1
from table1);
If you're trying to delete from table1, then that's the table name that has to be used in the delete clause, not table2.
delete table1 t1
where exists (select null
from table2 t2
where t2.column2 = t1.column1)
Related
I have two tables with same structure that can have duplicated records, I want to identify which ones from table 2 already exists in table 1 and delete them from table 2. The following SELECT returns the duplicated records I want to delete. None of these tables have a primary key, so I need to do multiple 'ON' to identify unique records.
SELECT V.*
FROM table2 AS V
INNER JOIN table1 AS N
ON V.column1 = N.column1 AND V.column2 = N.column2 AND V.column3= N.column3;
Then I insert this as a subquery for the DELETE:
DELETE FROM table2
WHERE table2.column1 IN
(SELECT V.*
FROM table2 AS V
INNER JOIN table1 AS N
ON V.column1 = N.column1 AND V.column2 = N.column2 AND V.column3= N.column3);
When running this query I get the following error:
You have written a query that can return more than one field without using the reserved word EXISTS in the FROM clause of the main query. Correct the SELECT instruction of the subquery to request a single field.
I also tried this way, but it deletes all the records from table 2, not only the result of the subquery:
DELETE FROM table2
WHERE EXISTS
(SELECT V.*
FROM table2 AS V
INNER JOIN table1 AS N
ON V.column1 = N.column1 AND V.column2 = N.column2 AND V.column3= N.column3);
This is the first solution I came up with, but I'm wondering if it wouldn't be easier to do in MS Access inserting into table1 all the records from table2 that doesn't match, and then delete table2.
All sugestions will be appreciated :)
Take the advice of the error message and try using exists logic:
DELETE
FROM table2 t2
WHERE EXISTS (SELECT 1 FROM table1 t1
WHERE t1.column1 = t2.column1 AND
t1.column2 = t2.column2 AND
t1.column3 = t2.column3);
The problem with your current exists attempt is that the query inside the EXISTS clause always has a result set, and that result set is independent of the outer delete call. So, all records get deleted.
I think you're just missing the specific column in your subquery.
This should work better :
DELETE FROM table2
WHERE table2.column1 IN
(SELECT V.column1
FROM table2 AS V
INNER JOIN table1 AS N
ON V.column1 = N.column1 AND V.column2 = N.column2 AND V.column3= N.column3);
I am trying to delete rows from one table. So this what i have done so far. I imported a .CSV file which created a temp table. I would like to delete the rows in my original table with matching with temp table.
I tried the following code :
Delete From Table1
Where postid and userid in (Select postid, userid
from Table2)
but it does not work.
The goal is to delete rows in Table 1 using Table 2.
A simple INNER JOIN should do the job:
DELETE T1
FROM Table1 T1
INNER JOIN Table2 T2
ON T1.postid = T2.postid
AND T1.userid = T2.userid
This is just another funny way :
DELETE FROM Table1
WHERE STR(postid) + STR(userid)
IN (SELECT STR(postid) + STR(userid) FROM Table2)
As far as I understand you want to Delete from Table1 where you want to create a composite condition based on postid and userid the from Table2 the problem is that you subquery in(Select postid,userid from
Table2) is not returning the correct value as to match the in condition please modify the query to
DELETE T1
FROM Table1 T1
INNER JOIN Table2 T2
ON T1.postid = T2.postid
AND T1.userid = T2.userid
as stated in the previous answer
You can use a Merge statement. In this case you're only interested in deletes. A semicolon is required after the delete section, followed by a final semicolon to end the merge statement. For example:
MERGE table1 AS target USING table2 AS source
ON target.postid = source.postid and target.userid = source.userid
WHEN Matched THEN DELETE;;
An example sqlfiddle: http://sqlfiddle.com/#!18/a932d/1/0
The Merge documentation: https://learn.microsoft.com/en-us/sql/t-sql/statements/merge-transact-sql
I can't seem to ever remember this query!
I want to delete all rows in table1 whose ID's are the same as in Table2.
So:
DELETE table1 t1
WHERE t1.ID = t2.ID
I know I can do a WHERE ID IN (SELECT ID FROM table2) but I want to do this query using a JOIN if possible.
DELETE t1
FROM Table1 t1
JOIN Table2 t2 ON t1.ID = t2.ID;
I always use the alias in the delete statement as it prevents the accidental
DELETE Table1
caused when failing to highlight the whole query before running it.
DELETE Table1
FROM Table1
INNER JOIN Table2 ON Table1.ID = Table2.ID
There is no solution in ANSI SQL to use joins in deletes, AFAIK.
DELETE FROM Table1
WHERE Table1.id IN (SELECT Table2.id FROM Table2)
Later edit
Other solution (sometimes performing faster):
DELETE FROM Table1
WHERE EXISTS( SELECT 1 FROM Table2 Where Table1.id = Table2.id)
PostgreSQL implementation would be:
DELETE FROM t1
USING t2
WHERE t1.id = t2.id;
Try this:
DELETE Table1
FROM Table1 t1, Table2 t2
WHERE t1.ID = t2.ID;
or
DELETE Table1
FROM Table1 t1 INNER JOIN Table2 t2 ON t1.ID = t2.ID;
I think that you might get a little more performance if you tried this
DELETE FROM Table1
WHERE EXISTS (
SELECT 1
FROM Table2
WHERE Table1.ID = Table2.ID
)
This will delete all rows in Table1 that match the criteria:
DELETE Table1
FROM Table2
WHERE Table1.JoinColumn = Table2.JoinColumn And Table1.SomeStuff = 'SomeStuff'
Found this link useful
Copied from there
Oftentimes, one wants to delete some records from a table based on criteria in another table. How do you delete from one of those tables without removing the records in both table?
DELETE DeletingFromTable
FROM DeletingFromTable INNER JOIN CriteriaTable
ON DeletingFromTable.field_id = CriteriaTable.id
WHERE CriteriaTable.criteria = "value";
The key is that you specify the name of the table to be deleted from as the SELECT. So, the JOIN and WHERE do the selection and limiting, while the DELETE does the deleting. You're not limited to just one table, though. If you have a many-to-many relationship (for instance, Magazines and Subscribers, joined by a Subscription) and you're removing a Subscriber, you need to remove any potential records from the join model as well.
DELETE subscribers, subscriptions
FROM subscribers INNER JOIN subscriptions
ON subscribers.id = subscriptions.subscriber_id
INNER JOIN magazines
ON subscriptions.magazine_id = magazines.id
WHERE subscribers.name='Wes';
Deleting records with a join could also be done with a LEFT JOIN and a WHERE to see if the joined table was NULL, so that you could remove records in one table that didn't have a match (like in preparation for adding a relationship.) Example post to come.
Since the OP does not ask for a specific DB, better use a standard compliant statement.
Only MERGE is in SQL standard for deleting (or updating) rows while joining something on target table.
merge table1 t1
using (
select t2.ID
from table2 t2
) as d
on t1.ID = d.ID
when matched then delete;
MERGE has a stricter semantic, protecting from some error cases which may go unnoticed with DELETE ... FROM. It enforces 'uniqueness' of match : if many rows in the source (the statement inside using) match the same row in the target, the merge must be canceled and an error must be raised by the SQL engine.
To Delete table records based on another table
Delete From Table1 a,Table2 b where a.id=b.id
Or
DELETE FROM Table1
WHERE Table1.id IN (SELECT Table2.id FROM Table2)
Or
DELETE Table1
FROM Table1 t1 INNER JOIN Table2 t2 ON t1.ID = t2.ID;
I often do things like the following made-up example. (This example is from Informix SE running on Linux.)
The point of of this example is to delete all real estate exemption/abatement transaction records -- because the abatement application has a bug -- based on information in the real_estate table.
In this case last_update != nullmeans the account is not closed, and res_exempt != 'p' means the accounts are not personal property (commercial equipment/furnishings).
delete from trans
where yr = '16'
and tran_date = '01/22/2016'
and acct_type = 'r'
and tran_type = 'a'
and bill_no in
(select acct_no from real_estate where last_update is not null
and res_exempt != 'p');
I like this method, because the filtering criteria -- at least for me -- is easier to read while creating the query, and to understand many months from now when I'm looking at it and wondering what I was thinking.
Referencing MSDN T-SQL DELETE (Example D):
DELETE FROM Table1
FROM Tabel1 t1
INNER JOIN Table2 t2 on t1.ID = t2.ID
This is old I know, but just a pointer to anyone using this ass a reference. I have just tried this and if you are using Oracle, JOIN does not work in DELETE statements.
You get a the following message:
ORA-00933: SQL command not properly ended.
While the OP doesn't want to use an 'in' statement, in reply to Ankur Gupta, this was the easiest way I found to delete the records in one table which didn't exist in another table, in a one to many relationship:
DELETE
FROM Table1 as t1
WHERE ID_Number NOT IN
(SELECT ID_Number FROM Table2 as t2)
Worked like a charm in Access 2016, for me.
delete
table1
from
t2
where
table1.ID=t2.ID
Works on mssql
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
I can't seem to ever remember this query!
I want to delete all rows in table1 whose ID's are the same as in Table2.
So:
DELETE table1 t1
WHERE t1.ID = t2.ID
I know I can do a WHERE ID IN (SELECT ID FROM table2) but I want to do this query using a JOIN if possible.
DELETE t1
FROM Table1 t1
JOIN Table2 t2 ON t1.ID = t2.ID;
I always use the alias in the delete statement as it prevents the accidental
DELETE Table1
caused when failing to highlight the whole query before running it.
DELETE Table1
FROM Table1
INNER JOIN Table2 ON Table1.ID = Table2.ID
There is no solution in ANSI SQL to use joins in deletes, AFAIK.
DELETE FROM Table1
WHERE Table1.id IN (SELECT Table2.id FROM Table2)
Later edit
Other solution (sometimes performing faster):
DELETE FROM Table1
WHERE EXISTS( SELECT 1 FROM Table2 Where Table1.id = Table2.id)
PostgreSQL implementation would be:
DELETE FROM t1
USING t2
WHERE t1.id = t2.id;
Try this:
DELETE Table1
FROM Table1 t1, Table2 t2
WHERE t1.ID = t2.ID;
or
DELETE Table1
FROM Table1 t1 INNER JOIN Table2 t2 ON t1.ID = t2.ID;
I think that you might get a little more performance if you tried this
DELETE FROM Table1
WHERE EXISTS (
SELECT 1
FROM Table2
WHERE Table1.ID = Table2.ID
)
This will delete all rows in Table1 that match the criteria:
DELETE Table1
FROM Table2
WHERE Table1.JoinColumn = Table2.JoinColumn And Table1.SomeStuff = 'SomeStuff'
Found this link useful
Copied from there
Oftentimes, one wants to delete some records from a table based on criteria in another table. How do you delete from one of those tables without removing the records in both table?
DELETE DeletingFromTable
FROM DeletingFromTable INNER JOIN CriteriaTable
ON DeletingFromTable.field_id = CriteriaTable.id
WHERE CriteriaTable.criteria = "value";
The key is that you specify the name of the table to be deleted from as the SELECT. So, the JOIN and WHERE do the selection and limiting, while the DELETE does the deleting. You're not limited to just one table, though. If you have a many-to-many relationship (for instance, Magazines and Subscribers, joined by a Subscription) and you're removing a Subscriber, you need to remove any potential records from the join model as well.
DELETE subscribers, subscriptions
FROM subscribers INNER JOIN subscriptions
ON subscribers.id = subscriptions.subscriber_id
INNER JOIN magazines
ON subscriptions.magazine_id = magazines.id
WHERE subscribers.name='Wes';
Deleting records with a join could also be done with a LEFT JOIN and a WHERE to see if the joined table was NULL, so that you could remove records in one table that didn't have a match (like in preparation for adding a relationship.) Example post to come.
Since the OP does not ask for a specific DB, better use a standard compliant statement.
Only MERGE is in SQL standard for deleting (or updating) rows while joining something on target table.
merge table1 t1
using (
select t2.ID
from table2 t2
) as d
on t1.ID = d.ID
when matched then delete;
MERGE has a stricter semantic, protecting from some error cases which may go unnoticed with DELETE ... FROM. It enforces 'uniqueness' of match : if many rows in the source (the statement inside using) match the same row in the target, the merge must be canceled and an error must be raised by the SQL engine.
To Delete table records based on another table
Delete From Table1 a,Table2 b where a.id=b.id
Or
DELETE FROM Table1
WHERE Table1.id IN (SELECT Table2.id FROM Table2)
Or
DELETE Table1
FROM Table1 t1 INNER JOIN Table2 t2 ON t1.ID = t2.ID;
I often do things like the following made-up example. (This example is from Informix SE running on Linux.)
The point of of this example is to delete all real estate exemption/abatement transaction records -- because the abatement application has a bug -- based on information in the real_estate table.
In this case last_update != nullmeans the account is not closed, and res_exempt != 'p' means the accounts are not personal property (commercial equipment/furnishings).
delete from trans
where yr = '16'
and tran_date = '01/22/2016'
and acct_type = 'r'
and tran_type = 'a'
and bill_no in
(select acct_no from real_estate where last_update is not null
and res_exempt != 'p');
I like this method, because the filtering criteria -- at least for me -- is easier to read while creating the query, and to understand many months from now when I'm looking at it and wondering what I was thinking.
Referencing MSDN T-SQL DELETE (Example D):
DELETE FROM Table1
FROM Tabel1 t1
INNER JOIN Table2 t2 on t1.ID = t2.ID
This is old I know, but just a pointer to anyone using this ass a reference. I have just tried this and if you are using Oracle, JOIN does not work in DELETE statements.
You get a the following message:
ORA-00933: SQL command not properly ended.
While the OP doesn't want to use an 'in' statement, in reply to Ankur Gupta, this was the easiest way I found to delete the records in one table which didn't exist in another table, in a one to many relationship:
DELETE
FROM Table1 as t1
WHERE ID_Number NOT IN
(SELECT ID_Number FROM Table2 as t2)
Worked like a charm in Access 2016, for me.
delete
table1
from
t2
where
table1.ID=t2.ID
Works on mssql