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);
Related
I have the following SQL code (this is how much I've got so far):
MERGE INTO SCHEMA1.TABLE_1 table1 USING
(
SELECT DISTINCT table2.column1,
view1.column2
FROM SCHEMA2.TABLE_2 table2
LEFT JOIN SCHEMA2.VIEW_1 view1
ON table2.column2 = view1.column3
) t2 ON (table1.column3 = t2.column1 )
WHEN MATCHED THEN
UPDATE
SET table1.column4 = t2.column2;
The following is the definition of VIEW_1 :
CREATE VIEW SCHEMA_2.VIEW_1
AS (SELECT
SCHEMA_2.TABLE_1.COLUMN_1,
SCHEMA_2.TABLE_2.COLUMN_1,
SCHEMA_2.TABLE_2.COLUMN_2,
SCHEMA_2.TABLE_2.COLUMN_3,
SCHEMA_2.TABLE_5.COLUMN_1,
SCHEMA_2.TABLE_6.COLUMN_1,
SCHEMA_2.TABLE_6.COLUMN_2,
SCHEMA_2.TABLE_6.COLUMN_3,
SCHEMA_2.TABLE_6.COLUMN_4,
SCHEMA_2.TABLE_7.COLUMN_1,
SCHEMA_2.TABLE_7.COLUMN_2,
SCHEMA_2.TABLE_8.COLUMN_1
FROM SCHEMA_2.TABLE_1
INNER JOIN SCHEMA_2.TABLE_2
ON SCHEMA_2.TABLE_1.COLUMN_1 = SCHEMA_2.TABLE_2.COLUMN_2
INNER JOIN SCHEMA_2.TABLE_5
ON SCHEMA_2.TABLE_1.COLUMN_4 = SCHEMA_2.TABLE_5.COLUMN_3
LEFT OUTER JOIN SCHEMA_2.TABLE_6
ON SCHEMA_2.TABLE_2.COLUMN_2 = SCHEMA_2.TABLE_6.COLUMN_4
LEFT OUTER JOIN SCHEMA_2.TABLE_7
ON SCHEMA_2.TABLE_2.COLUMN_1 = SCHEMA_2.TABLE_8.COLUMN_5
);
But I'm getting the below error message:
Error report -
SQL Error: ORA-30926: unable to get a stable set of rows in the source tables
30926. 00000 - "unable to get a stable set of rows in the source tables"
*Cause: A stable set of rows could not be got because of large dml
What causes the error? Where to change in the code to make it work?
Thanks for helping out!
For this example your problem is definitely in the USING subquery. This query produces more than one value of table2.column1:
SELECT DISTINCT table2.column1,
view1.column2
FROM SCHEMA2.TABLE_2 table2
LEFT JOIN SCHEMA2.VIEW_1 view1
ON table2.column2 = view1.column3
So the ON clause will match the same row(s) in table1 more than once:
ON (table1.column3 = t2.column1 )
Oracle cannot figure out which value of t2.column2 should be used in the UPDATE, so it hurls ORA-30926.
Using distinct in the subquery doesn't help because that gives permutations of all the columns. You need to write a subquery which will produce unique values of t2.column1 across all rows, or add another identifying column(s) to generate a unique key you can join to table1.
In my experience, this error is returned, not only when the USING clause returns more than one row for a row in the MATCH table, but also frequently when it cannot be sure that only one row will be returned (even if there are no actual cases of multiple rows being returned). To force the parser to accept the query in cases like this, I usually resort to using a GROUP BY on the MATCH..ON column(s).
MERGE INTO SCHEMA1.TABLE_1 table1 USING
(
SELECT table2.column1,
MAX(view1.column2) as column2
FROM SCHEMA2.TABLE_2 table2
LEFT JOIN SCHEMA2.VIEW_1 view1
ON table2.column2 = view1.column3
GROUP BY table2.column1
) t2 ON (table1.column3 = t2.column1 )
WHEN MATCHED THEN
UPDATE
SET table1.column4 = t2.column2;
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.
I need to join two tables together based on a three-column key stack. The problem is sometimes one of the key columns is translated and mapped differently in another table. I will attempt to example my issue using code:
select t1.TQ
from table1 t1
left join table2 t2 on t1.comp_cd = t2.comp_cd and t1.plcy_frm = t2.plcy_frm
and t1.val_cd = t2.val_cd
The columns "comp_cd" and "plcy_frm" are fine, however the problem is with val_cd. Sometimes the val_cd in table2 does not map correctly to table1 and must go through a third table, table3. Table3 structure is below:
Val_Cd Mapped_Val_Cd
A123 A564
So -> I need to join on Mapped_Val_Cd value when it exists in Table3, but join on Val_Cd from Table2 when Val_Cd does not exist in Table3.
I hope this makes sense - I have tried Case when exists syntax but cannot get that to work.
Assuming there are no duplicates in table3, you can left join it in and then choose the value that you want in the on clause:
select t1.TQ
from table1 t1 left join
table3 t3
on t1.val_cd = t3.val_cd
table2 t2
on t1.comp_cd = t2.comp_cd and
t1.plcy_frm = t2.plcy_frm and
t1.val_cd = coalesce(t3.Mapped_Val_Cd, t2.val_cd);
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 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