I have two tables in a SQL Server 2008 environment with the following structure
Table1
- ID
- DescriptionID
- Description
Table2
- ID
- Description
Table1.DescriptionID maps to Table2.ID. However, I do not need it any more. I would like to do a bulk update to set the Description property of Table1 to the value associated with it in Table2. In other words I want to do something like this:
UPDATE
[Table1]
SET
[Description]=(SELECT [Description] FROM [Table2] t2 WHERE t2.[ID]=Table1.DescriptionID)
However, I'm not sure if this is the appropriate approach. Can someone show me how to do this?
Your way is correct, and here is another way you can do it:
update Table1
set Description = t2.Description
from Table1 t1
inner join Table2 t2
on t1.DescriptionID = t2.ID
The nested select is the long way of just doing a join.
Your approach is OK
Maybe slightly clearer (to me anyway!)
UPDATE
T1
SET
[Description] = t2.[Description]
FROM
Table1 T1
JOIN
[Table2] t2 ON t2.[ID] = t1.DescriptionID
Both this and your query should run the same performance wise because it is the same query, just laid out differently.
You can do this through a regular UPDATE with a JOIN
UPDATE T1
SET Description = T2.Description
FROM Table1 T1
JOIN Table2 T2
ON T2.ID = T1.DescriptionId
Or you can simply update without using join like this:
Update t1 set t1.Description = t2.Description from #tbl2 t2,tbl1 t1
where t1.ID= t2.ID
The SQL you posted in your question is one way to do it. Most things in SQL have more than one way to do it.
UPDATE
[Table1]
SET
[Description]=(SELECT [Description] FROM [Table2] t2 WHERE t2.[ID]=Table1.DescriptionID)
If you are planning on running this on a PROD DB, it is best to create a snapshot or mirror of it first and test it out. Verify the data ends up as you expect for a couple records. And if you are satisfied, run it on the real DB.
Related
I'm trying to update certain columns from one DB to another in tables whose Id columns align.
I have the query below, but I fear it will update all rows because the IN clause values aren't being matched.
How do I match all those values within the IN clause to the relevant column from Table1? Or is this correct as is?
UPDATE Table1
SET NAME = T2.Name
FROM OTHERDB.[Table2] as T2
WHERE T2.Id in
(
'12345678'
--...
}
Your suspicions are correct: your query will update every row.
You need a join:
UPDATE T1
SET NAME = T2.Name
FROM Table1 T1
JOIN OTHERDB.Table2 as T2 ON T2.Id = T1.Id
WHERE T1.Id in (
'12345678',
...
}
This assumes that Id columns match up between databases. If that’s not the case, the join/where clauses would need adjustment.
Using an inner join means if there’s no corresponding data in the other database, there won’t be an update to null.
The where clause now looks up on the local table’s Id for efficiency.
You can try the following:
UPDATE Table1
SET Table1.Name = T2.Name
FROM OtherDB.Table2 T2
WHERE T2.Id IN
(
SELECT Id FROM Table1 (NOLOCK) WHERE ...
)
Former SQL Server dataminer here expanding my skills. Complete newbie to Oracle. I've run into multiple error messages trying to convert this SQL query to work in Oracle:
UPDATE table1
SET program = SUBSTR(table2.project,1,5)
FROM table1
LEFT OUTER JOIN table2
ON table1.id = table2.id
WHERE table1.program = 'THE_PROGRAM_NAME'
AND table2.program = 'THE_PROGRAM_NAME';
I've dealt with each error having gone through various StackOverflow questions, but none I've encountered have helped me resolve it fully. The basic problem is that Oracle doesn't want to deal with taking one line from the joined table to update multiple lines from the primary table, and I don't know how to address this.
All I've read so far seems to indicate that this is an insurmountable problem so I'm asking my own new question to have that confirmed or refuted, and either get a whole new approach to try or that so-far-elusive solution.
This is as far as I have gotten, and it's led me to "ORA-30926 unable to get a stable set of rows in the source tables":
MERGE INTO table1 ce
USING
(SELECT DISTINCT SUBSTR(table2.project,1,5) newvalue, table1.code, table1.id
FROM table1
LEFT OUTER JOIN table2
ON table1.id = table2.id
WHERE table1.program = 'THE_PROGRAM_NAME'
AND table2.program = 'THE_PROGRAM_NAME'
) combined
ON (ce.id = combined.id
AND ce.code = combined.code)
WHEN MATCHED THEN
UPDATE SET ce.program = combined.newvalue;
If you need more information to be able help please ask.
Any help greatly appreciated.
Regards,
Oracle does not support joins in update queries. A typical translation would use a correlated subquery:
UPDATE table1 t1
SET program = (
SELECT SUBSTR(t2.project,1,5)
FROM table2 t2
WHERE t1.id = t2.id AND t2.program = t1.program
)
WHERE program = 'THE_PROGRAM_NAME';
Note that this would update program to null if there is no match in table2. If you want to avoid that, then add a condition in the WHERE clause:
UPDATE table1 t1
SET program = (
SELECT SUBSTR(t2.project,1,5)
FROM table2 t2
WHERE t1.id = t2.id AND t2.program = t1.program
)
WHERE program = 'THE_PROGRAM_NAME' AND EXISTS (
SELECT 1
FROM table2 t2
WHERE t1.id = t2.id AND t2.program = t1.program
);
I am trying to achieve some logic on Oracle by using simple query and feeling stuck on it. The thing is that I cannot use PL-SQL and this is giving me some headached.
I have three tables with below values
I am trying to get something like:
SELECT T1.CODE,T2.CODE,T3.VALUE
FROM TABLE1 T1
JOIN TABLE2 T2 ON T1.REF = T2.CODE
JOIN TABLE3 T3 ON T2.REF = T3.CODE
WHERE T1.CODE = XXXXX
Result for XXXX = 98
98,2,CCC
Whenever the parameter XXXXX is 99,98,96,95 it returns what I was expecting but the logic I need doesnt work for 97.
My requirement says that in case i cannot find a link in Table2 then I should use always DEF in Table3 and leave unlinked values as NULL. Something like:
Result for XXXX = 97
97,NULL,AAA
I think it could be achieved in a not very "clean" way by using CASE statements but this is an example in which the number of columns shown is very minimal. In my real case it is extremelly bigger... So I want to try to avoid using CASE statements as it would raise the complexity of it a lot.
I tried with different methods but my low experience on Oracle cannot deep so much :)
Any way to achieve this without using PLSQL neither those CASE?
If I'm understanding correctly, you need to use an outer join instead. You can then use COALESCE to return the value associated with "DEF" if T2.REF is NULL:
SELECT T1.CODE,
T2.CODE,
T3.VALUE
FROM TABLE1 T1
LEFT JOIN TABLE2 T2 ON T1.REF = T2.CODE
LEFT JOIN TABLE3 T3 ON COALESCE(T2.REF,'DEF') = T3.CODE
WHERE T1.CODE = XXXXX
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